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Published online: 20th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)101
■ 1,2-cis-Selective Formation of a Unique Amino-Containing Amino Glycoside by Endocyclic Cleavage Strategy

Shino Manabe* and Yukishige Ito*

*Synthetic Cellular Chemistry Laboratory, RIKEN, Hirosawa, Wako, Saitama 351-0198, Japan

Abstract

2-Acetamido-4-amino-2,4,6-trideoxy-α-D-galactopyranoside (AAT), a unique aminated sugar unit, is often found in zwitterionic polysaccharides. Stereoselective formation of the 1,2-cis linkage of these unique sugar derivatives was achieved by an anomerization reaction based on an endocyclic cleavage process.

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Published online: 18th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)102
■ Synthesis of Di(3-thienyl)benzoporphyrin

Tetsuo Okujima,* Kota Muramatsu, Shigeki Mori, Masayoshi Takase, and Hidemitsu Uno

*Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan

Abstract

We have successfully synthesized 2,3-di(3-thienyl)benzo[b]porphyrin based on retro Diels–Alder reaction of bicyclo[2.2.2]octadiene(BCOD)-fused porphyrin and investigated its photoisomerization reaction.

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Published online: 15th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)94
■ Synthesis of a Poly-Heterocyclic Tetra-Substituted Alkene via a Palladium-Catalyzed Four-Fold Domino Reaction for the Design of Polymeric Molecular Switches

Taukeer A. Khan and Lutz F. Tietze*

*Institute of Organic and Biomolecular Chemistry, University of Goettingen, Tammannstrasse 2, 37077 Goettingen, Germany

Abstract

A facile synthesis of a complex poly-heterocyclic tetrasubstituted alkene 4 with intrinsic helical chirality containing two acrylate moieties suitable for polymerization is described. Compound 4 can act as a molecular switch and was prepared via a palladium-catalyzed four-fold domino reaction including two Sonogashira reactions and two domino-carbopalladation/C‒H-activation reactions.

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Published online: 15th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)97
■ Optimized Synthesis and Solid State Investigations on the Drug Candidate Encenicline Hydrochloride

Gerhard Laus, Sandro Neuner, Ramona Metz, Thomas Müller, Volker Kahlenberg, Thomas Gelbrich, Sven Nerdinger,* Erwin Schreiner, Verena Adamer, Klaus Wurst, and Herwig Schottenberger

*Global Portfolio, Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

For the production of drug substances a robust, scalable process delivering the active pharmaceutical ingredient (API) in excellent chemical and polymorphic purity is required. For this purpose we developed a novel imidazole-mediated one-pot procedure for the preparation of encenicline hydrochloride monohydrate, which crystallizes directly from the reaction mixture as pure non-hygroscopic polymorph (Form I). Solid state studies revealed a series of additional new physical forms for which crystal structures have been determined by single crystal X-ray diffraction.

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Published online: 14th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)100
■ Preparation of Tricyclic Analog as CDE Ring Model of Renieramycin Marine Natural Product by Novel Photo-Induced Transformation of 6-Methoxy 1,2,3,4-Tetrahydroisoquinoline-5,8-dione

Masashi Yokoya, Shohei Takahashi, and Naoki Saito*

*Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan

Abstract

2-Acetyl-6-[(benzyloxy)methyl]-9-methoxy-8-methyl-11,11a- dihydro-2H-pyrazino[1,2-b]isoquinoline-1,4,7,10(3H,6H)-tetraone (11a) was prepared as the CDE ring model of renieramycins, and its novel photo-induced transformation was demonstrated to construct a 1,3-dioxol ring.

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Published online: 14th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)103
■ Synthesis of Furan-Fused Silole and Phosphole by One-Pot Halogen Dance/Homocoupling of Bromofurfural Derivative

Kentaro Okano,* Yuki Murase, and Atsunori Mori

*Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan

Abstract

Synthesis of a furan-fused silole and phosphole was achieved through a one-pot halogen dance/homocoupling of a bromofurfural derivative followed by the formation of the silole and phosphole skeleton.

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Published online: 13th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)87
■ Asymmetric Synthesis of t-Butyl 3-Alkyl-oxindole-3-carboxylates via Chiral Phosphoric Acid Catalyzed Desymmetrization of Di-t-butyl 2-Alkyl-2-(2-aminophenyl)malonates

Kyoji Ishida, Masahiro Shimizu, Yu-suke Yamai, Itaru Natsutani, Shinichi Uesato, Yasuo Nagaoka, and Takaaki Sumiyoshi*

*Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Yamate-cho 3-3-35, Suita, Osaka, 564-8680, Japan

Abstract

We describe the asymmetric desymmetrization of di-t-butyl 2-alkyl-2-(2-aminophenyl)malonates to prepare enantioenriched t-butyl 3-alkyl-oxindole-3-carboxylates using (S)-TRIP, a chiral phosphoric acid. Optimization study increased the enantioselectivity up to 66% ee.

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Published online: 13th February, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-S(F)91
■ Synthetic Study of an Intermediates towards Paracentrone

Taiki Kaneyama, Kazumi Fujimaru, Mami Takemura, Kizuku Hasegawa, Masahiro Hamada, Takao Kishimoto, Daisuke Urabe, and Noriyuki Nakajima*

*Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Kosugi, Toyama 939-0398, Japan

Abstract

Paracentrone (1), the second naturally occurring C31-methyl ketone apocarotenoid from fucoxanthin (2), was first isolated from the sea urchin Paracentrotus lividus. In this study, we focused on this carotenoid metabolite and report on a synthetic approach towards (3E)-(5R)-[(2R,4S)-2-hydroxyl-4-(tert-butyldimethylsilyl)oxy-2,6,6-trimethylcyclohexylidene]-1-iodo-4-methyl-1,3,5-hexatriene (5), a synthetic intermediate towards 1. This was obtained from epoxy acetylene (11) via (2E)-(4R)-[(2R,4S)-2-hydroxyl-4-(tert-butyldimethylsilyl)oxy-2,6,6-trimethylcyclohexylidene]-3-methylpenta-2,4-diene-1-ol (7).

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Published online: 13th February, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14031
■ Synthesis of 1-Methoxyindoles and Related Analogs of Pimprinine, (±)-Chelonin A and B, Based on 1-Hydroxyindole Chemistry

Kazuko Aoki, Yoshiyuki Nagahama, Katsuko Sugaya, Yuki Maeda, Haruhiko Sato, Kyoko Nakagawa (Goto), and Masanori Somei*

*Noto Marine Laboratory, Institute of Nature and Environmental Technology, Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, 56-7 Matsuhidai, Matsudo-shi, Chiba 270-2214, Japan

Abstract

The total synthesis of pimprinine, (±)-chelonin A and B, and their analogs are achieved based on 1-hydroxyindole chemistry.

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Published online: 8th February, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)77
■ Tripeptide-catalyzed Asymmetric Aldol Reaction of Trifluoromethylated Aromatic Ketones with Acetone

Kazumasa Kon, Yoshihito Kohari,* and Miki Murata

*School of Earth, Energy and Environmental Engineering, Faculty of Engineering, Kitami Institute of Technology, 165 Koen-Cho, Kitami, Hokkaido 090-8507, Japan

Abstract

The development of H-Pro-Gly-Ala-OH (3d) to realize an inexpensive and simple organocatalytic system for the direct asymmetric aldol reaction of trifluoromethylated aromatic ketone 1 with acetone was achieved. The 3d-catalyzed aldol reaction of 1a–1j provided various aldol adducts 4a–4j with up to 81% yield and 77% ee. An investigation of the transition state via DFT calculations revealed that hydrogen bonding was important for the revelation of the enantioselectivity.

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Published online: 8th February, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14025
■ Site-Selective Acylation of Carbohydrates Directed by Recyclable Polymer-Supported Isothiourea Catalysts

Wang-Ze Song,* Kun Dong, Ming Li, Jun-Hao Li, Karim Ullah, and Yu-Bin Zheng

*School of Pharmaceutical Science and Technology, Dalian University of Technology, No.2 Linggong Road, Ganjingzi District, Dalian City, Liaoning Province 116024, China

Abstract

The polystyrene-supported isothiourea catalysts, derived from the homogeneous catalyst BTMs, were synthesized and applied to the site-selective acylation of carbohydrates. The catalysts can be recovered and reused conveniently for 10 cycles without significantly loss in either activity or selectivity. It offers a sustainable and environmentally benign approach for the site-selective functionalization of carbohydrates.

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Published online: 7th February, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)53
■ A Novel Rearrangement Reaction of Morphinan to Arylmorphan Skeletons and the Pharmacologies of Arylmorphan Derivatives

Masahiro Yata, Noriki Kutsumura, Yasuyuki Nagumo, Naoshi Yamamoto, Tsuyoshi Saitoh, Yukiko Ishikawa, Yoko Irukayama-Tomobe, Masashi Yanagisawa, and Hiroshi Nagase*

*International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan

Abstract

A novel rearrangement reaction of the morphinan skeleton by using zinc iodide was developed. The substrate-specific rearrangement afforded two types of novel 5-arylmorphan derivatives, i.e., compounds produced by either a 1,5-shift of the nitrogen bridge or a 1,3-shift of the nitrogen bridge in a starting morphinan derivative. The 5-arylmorphan derivatives showed selective κ opioid receptor activities even though many 5-arylmorphan compounds reported previously have shown selective µ opioid receptor activities. In addition, other related 5-arylmorphan derivatives showed potent dual antagonistic activities toward orexin 1 and 2 receptors.

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Published online: 7th February, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14024
■ Synthesis, Crystal Structure, Spectroscopic and Computational Studies of 2-{1-[2-(1,3-Dimethyl-4-nitro-1H-pyrazol-5-yl)hydrazono]ethyl}pyridine

Ahmad S. Abushamleh,* Kayed A. Abu-Safieh,* Monther A. Khanfar, Khaleel I. Assaf, Bader A. Salameh, and Nisreen J. Alwahsh

*Department of Chemistry, Faculty of Science, Hashemite University, P.O. Box 330127 Zarqa, 13133, Jordan

Abstract

2-{1-[2-(1,3-Dimethyl-4-nitro-1H-pyrazol-5-yl)hydrazono]ethyl}- pyridine has been prepared from 5-hydrazino-1,3-dimethyl-4-nitro-1H-pyrazole and 2-acetylpyridine in an ethanolic solution. It crystallizes as an (E/Z) isomeric pair in the triclinic space group P-1 with the lattice parameters: a = 10.357(1) Å, b = 11.613(1) Å, c = 13.069(1) Å, α = 67.74(1)°, β = 70.77(1)°, γ = 67.92(1)°, volume = 1315.6(3) Å3, Z = 2. The isomeric pair (E/Z) is contained in the unit cell, where the N-H group is H-bonded to the pyridine nitrogen and to the oxygen of the nitro group in the Z-isomer and to the oxygen of the nitro group only in the E-isomer. NMR showed that the E-isomer is the major. DFT calculations were performed to further investigate the electronic properties of the synthesized compound.

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Published online: 5th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)90
■ A Novel Route to (R)-2-(3-Chlorophenyl)propan-1-amine, a Key Intermediate for the Synthesis of Lorcaserin

Ivana Gazic Smilovic, Sven Nerdinger,* Sandro Neuner, Herwig Schottenberger, Thomas Gelbrich, and Klaus Wurst

*Global Portfolio, Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

A new and efficient three-step synthesis of (R)-2-(3-chlorophenyl)propan-1-amine is reported, which serves as an intermediate in the synthesis of the antiobesity drug lorcaserin. The key step is a chiral resolution due to the formation of a salt with l-(-)-3-phenyllactic acid. The structure of the relevant salt phase is reported.

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Published online: 5th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)84
■ Synthesis of N-Heterocyclic Carbene Ligands for Site-Selective C-H Alkylation by Cooperative Nickel/Aluminum Catalysis

Shogo Okumura, Tomohiro Ebara, Kazuhiko Semba, and Yoshiaki Nakao*

*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoudai-katsura, Nishikyo, Kyoto 615-8510, Japan

Abstract

We report synthesis of N-heterocyclic carbenes (NHCs), N,N'-bis{2,6-bis(3,5-dialkylphenyl)methy-4-methoxyphenyl}imidazol-2-ylidenes {alkyl = ethyl (L2) or n-propyl (L3)} and their applications to nickel-catalyzed C–H alkylation reactions of arenes. They showed site-selectivities and/or yields higher than NHCs used previously for the reactions.

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Published online: 4th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)86
■ Packing and Thin-Film Structures of 5,7,12,14-Tetra(α-Alkylthienylethyl)pentacenes

Hiroki Makino, Shin Sato, Junro Yoshino, Naoto Hayashi,* and Hiroyuki Okada*

*Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan

Abstract

Four 5,7,12,14-tetra(thienylethynyl)pentacenes (2–5) bearing H, Me, C5H11, and C6H13 groups at the α-positions of the thienyl groups were synthesized. The α-alkylthienyl groups enhanced solubilities of 2–5, whereas their ultraviolet/visible spectra were virtually identical. X-Ray diffraction revealed that the packing structure of 4 and 5 were significantly different because of one methylene group in each alkyl group. The thin-film structure of 4 was amorphous, while that of 5 consisted of small crystalline needles. Neither 4 nor 5 behaved as organic field-effect transistors because of inadequate packing and thin-film structure.

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Published online: 1st February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)98
■ Stereospecific Ring-Expanding Skeletal Rearrangement of Isoindoline to Tetrahydroisoquinoline via a Sequential Aziridine Ring Formation/Opening

Kenichi Kobayashi,* Ryusei Endo, Yusuke Honma, Emi Kasahara, Haruka Saito, Kosaku Tanaka III, Momoko Suzuki, and Hiroshi Kogen*

*Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

A stereospecific skeletal rearrangement of isoindoline to tetrahydroisoquinoline was developed under Appel reaction conditions using a combination of PPh3 and CCl4. This reaction involves a sequential ring formation/opening of a labile aziridine and enables the construction of a quaternary carbon center, offering a highly useful method for accessing 3,3,4-trisubstituted tetrahydroisoquinolines.

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Published online: 1st February, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14015
■ Bis-Heterocycles. Part II. Tetrahydro-3,3'-bi(1,2,4,5-oxatriazines)

Mustafa M. El-Abadelah, Firas F. Awwadi, Monther S. Zreid, and Mohammed M. Abadleh*

*Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, University of Petra, Amman 11196, Jordan

Abstract

A new set of tetrahydro-3,3'-bi(1,2,4,5-oxatriazines) 3a-e has been prepared via condensation reaction of alkanone- and cycloalkanone N-methylhydrazones with bis-nitrile oxide. Structures of the synthesized bis-heterocycles are based on IR, NMR and MS spectral data and further confirmed by single-crystal X-ray diffraction analysis for compounds 3a and 3d. Compound 3c exhibited inhibitory activity against butyrylcholinesterase (BChE) with IC50 = 1.75 × 10-5 μM.

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Published online: 31st January, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-S(F)81
■ Ring-Opening Metathesis of N-Alkenyl β-Lactams

Sambasivarao Kotha,* Sunil Pulletikurti, and Yuvaraj Dommaraju

*Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400 076, India

Abstract

We have synthesized a new class of N-alkenylated β-lactam derivatives and studied their metathetic behavior. Here, ring-opening metathesis is more favorable than ring-rearrangement metathesis. Molecular modelling studies revealed that the orientation of two olefinic moieties of β-lactam derivatives are far apart and therefore ring-rearrangement metathesis did not occur and ring-opening metathesis is only feasible.

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Published online: 29th January, 2019

Review | Special issue | Prepress
DOI: 10.3987/REV-18-SR(F)4
■ Mini-Review: Organic Catalysts in the 1,3-Dipolar Cycloaddition Reactions of Nitrile Oxides

Silvia Roscales* and Joaquín Plumet*

*Complutense University, Faculty of Chemistry, Organic Chemistry Department, Ciudad Universitaria, 28040, Madrid, Spain

Abstract

In 1961, Huisgen categorized the nitrile oxides (NOs) as a member of a broader class of 1,3-dipoles that were capable of undergoing 1,3-dipolar cycloaddition (DC) reactions. Nevertheless, the cycloaddition (CA) reactions of NOs to alkenes and alkynes are in many cases hampered by the tendency to the dimerization of the NO to the related furoxan (1,2,5-oxadiazole 2-oxide). In addition, although monosubstituted alkenes and alkynes show high regioselectivity in their cycloadditions with NOs, 1,2-disubstituted derivatives often give mixtures of regioisomers. Catalyzed NOs cycloadditions constitute in many cases an appropriate response to these problems and, in particular, the metal catalyzed cycloaddition reactions have been extensively used. However, the cost, toxicity and removal of trace amounts of the metal residues from desired products is quite costly and challenging, while crucial, especially in the pharmaceutical industry. Obviously, alternative pathways under metal-free conditions to fulfill the metal-catalyzed reactions are highly appealing. The present review is devoted to the consideration of the use of organic molecules as catalysts for 1,3-dipolar cycloaddition reactions of nitrile oxides.

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Published online: 29th January, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)93
■ Vicinal Functionalization of Uracil Heterocycles with Base Activation of Iodonium(III) Salts

Naoko Takenaga,* Shohei Ueda, Takumi Hayashi, Toshifumi Dohi, and Shinji Kitagaki

*Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan

Abstract

We describe a new approach for the construction of bicyclic uracil systems and vicinal functionalization by utilizing uracil-iodonium(III) salts. Our method efficiently furnishes various multi-functionalized uracil derivatives in a single step.

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Published online: 29th January, 2019

Review | Regular issue | Prepress
DOI: 10.3987/REV-18-898
■ Divergent Synthesis of Steroid Analogs from Steroidal β-Formylenamides, Conjugated Enones and β-Formylvinyl Halides

Geetmani S. Nongthombam and Romesh C. Boruah*

*Chemical Science and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat, Assam, India 785006

Abstract

In the past two decades, our laboratory has been actively engaged in the design and synthesis of novel heterosteroidal analogues. Three functional groups namely β-formylenamide, conjugated enone and β-formylvinyl halide were primarily employed in various reactions to afford a library of novel heterosteroids. The synthetic strategies have been concomitantly utilized in the relevant non-steroidal β-formylenamides, conjugated enones and β-formylvinyl halides.

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Published online: 25th January, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)64
■ Problem of Regioselectivity in the Amination of 2-Fluoro-5-iodopyridine with Adamantylalkyl Amines

Anton S. Abel, Yury N. Kotovshchikov, Alexei D. Averin,* Olga A. Maloshitskaya, Evgenii N. Savelyev, Boris S. Orlinson, Ivan A. Novakov, and Irina P. Beletskaya

*Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1-3, 119991, Moscow, Russia

Abstract

Cu(I)-Catalyzed and catalyst-free amination of 2-fluoro-5-iodopyridine with adamantylalkyl amines possessing different steric hindrances at amino group was investigated to obtain corresponding 5-amino-2-fluoro- and 2-amino-5-iodopyridines. The competition between catalytic substitution of iodine and non-catalytic substitution of fluorine was shown to take place. The catalytic system CuI/2-(isobutyryl)cyclohexanone in DMF provided yields of 5-amino-2-fluoropyridines up to 58% with stoichiometric ratio of the reagents and up to 98% with two equiv. of amines. The non-catalytic amination of 2-fluoro-5-iodopyridine provided the yields of 2-amino-5-iodopyridines up to 97%.

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Published online: 25th January, 2019

Review | Special issue | Prepress
DOI: 10.3987/REV-18-SR(F)6
■ Introducing a Methyl Group into Pyridines and Quinolines: A Mini-Review

Eliezer Falb and Alfred Hassner*

*Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002, Israel

Abstract

Pyridines are ubiquitous N-heterocycles that are present in many natural products and synthetic drugs with important biological applications. Introduction into a pyridine of a methyl (Me) or an isotopically labeled methyl group at carbon can alter its biological properties. However, regioselective introduction of a Me group in high yield, and preferably in a green manner, is often quite challenging. In this mini-review, several methods, most of which are recent, are examined whereby a Me or CD3 is introduced at a specific carbon in pyridines, as well as in some quinolines.

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Published online: 24th January, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14006
■ Reaction of 2,3,5,6,7,8-Hexahydroquinoxaline with Thiourea Derivatives: Analysis of the Structure and Conformational State of [4.4.3]Propellane

Kazuhide Nakahara,* Koki Yamaguchi, and Hisao Kansui

*Department of Integrative Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan

Abstract

The reaction of 2,3,5,6,7,8-hexahydroquinoxaline with thiourea derivatives yields a propellane-type tetraazaindene structure, whose conformation was established by 2D NMR analysis and molecular orbital calculations, and verified by single-crystal X-ray diffraction analysis. Further, the result obtained from X-ray analysis of this propellane-type tetraazaindene structure indicated that the crystalline state was stabilized by specific hydrogen bonds; four hydrogen bonds were of the type >C=S•••H–N, four of N–H•••N type between the imidazolidine moieties, and two of >C=S•••H–C type.

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Published online: 22nd January, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)96
■ A De Novo Asymmetric Synthesis of Phomopsolide E: A Practical Conversion from Phomopsolide D

Joel M. Harris, Miaosheng Li, and George A. O'Doherty*

*Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA.

Abstract

A practical three-step synthesis of phomopsolide E has been developed from a synthetic sample of phomopsolide D in three steps at 62% yield. A de novo asymmetric synthesis of phomopsolide D was accomplished in 8 steps from an achiral dienone in 47% yield. The initial asymmetry of phomopsolide E was installed by a Sharpless asymmetric dihydroxylation, whereas, a highly diastereoselective reagent control iterative asymmetric hydrogenation reaction was used to diastereoselectively install the pyranone stereochemistry. The net synthetic effort of phomopsolide E was accomplished in a total 11 steps in 40% overall yield. The route as devised provided for the first-time access to synthetic material for biological analysis and established both the absolute and relative stereochemistry for this natural product.

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Published online: 22nd January, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14016
■ Efficient Synthesis of Chiral 5-Methoxycarbonyl Pyridin-2(1H)-Ones and 3-Bromo-5-methoxycarbonyl Pyridin-2(1H)-ones

Hugo Pilotzi, Dino Gnecco,* María L. Orea,* David M. Aparicio, Sylvain Bernes, Jorge R. Juárez, and Joel L. Terán

*Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif. IC9 Complejo de Ciencias, C.U., 72570 Puebla, Mexico

Abstract

Starting from the mixture methyl-(S)-3-(1-phenylethylamino)acrylate 1-(E,Z) and the mixture methyl (R)-3-(2-(tert-butyldimethylsilyl)oxy-1-phenylethyl)amino acrylate 2-(E,Z) were synthesized the corresponding chiral 5-carbomethoxy-pyridin-2(1H)-ones in high yield. Finally, starting from these chiral pyridin-2(1H)-ones were prepared the corresponding 3-bromo-5-carbomethoxy-pyridin-2(1H)-ones in high yield.

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Published online: 22nd January, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14020
■ 4,6-Diacetylresorcinol in Heterocyclic Synthesis Part II: Synthesis of Some Novel 4,6-Bis(azolyl/azinyl/azepinyl)resorcinols

Mohammed A. Assiri, Tarik E. Ali,* Magdy A. Ibrahim, E. M. El-Amin, and I. S. Yahia

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt

Abstract

A series of new 4,6-bis(azolyl/azinyl/azepinyl)resorcinols was synthesized in a combinatorial manner besides, (2E,2'E)-4,6-bis[3-(aminophenyl-substituted)prop-2-en-1-oxo-1-yl]resorcinols were also obtained. Heterocyclization of (2E,2'E)-4,6-bis[3-(dimethylamino)prop-2-en-1-oxo-1-yl]resorcinol (2) with nitrogen-containing binucleophiles afforded the target compounds. All the newly synthesized compounds were characterized by spectral tools.

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Published online: 21st January, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)92
■ Synthesis and Stereochemical Analysis of Dynamic Planar Chiral Nine-Membered Diallylic Amide: Significant Substituent Effect on Stereochemical Stability

Jun-ichi Hayashi, Kazuhiro Uehara, Yusuke Ano, Yuuya Kawasaki, Kazunobu Igawa, and Katsuhiko Tomooka*

*Department of Molecular and Material Sciences, Institute for Materials Chemistry and Engineering, and IRCCS, Kyushu University, Kasuga, Fukuoka 816-8580, Japan

Abstract

C4-Methyl substituted nine-membered diallylic cyclic amide 1ac was synthesized. HPLC analysis using a chiral stationary phase revealed the presence of isolable enantiomers, whose absolute stereochemistry were determined by X-ray analysis. Studies on the stereochemical stability of 1ac showed that its chirality is more labile than that of the non-substituted congener 1aa and C3-methyl substituted congener 1ab.

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Published online: 21st January, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-14010
■ Divergent Synthesis of 5,6- and 3,6-Dihydropyridin-2(1H)-one via Intramolecular Knoevenagel Condensation

Arturo Bocardo-Bautista, María L. Orea, Jorge R. Juárez, Dino Gnecco, David M. Aparicio,* and Joel L. Terán*

*Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif. IC9, Complejo de Ciencias, C.U. 72570 Puebla, Pue., México.

Abstract

A simple and friendly strategy for the regioselective synthesis of 5,6- and 3,6-dihydropyridin-2(1H)-one via intramolecular Knoevenagel condensation from a common methyl 3-((2-(1,3-dioxolan-2-yl)ethyl)alkylamino)-3-oxopropanoate under acidic conditions is reported.

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