Online article for Non-subscribers

Pay per view

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact:

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

Paper | Special issue | Vol 95, No. 1, 2017, pp.223-231
Published online, 3rd August, 2016
DOI: 10.3987/COM-16-S(S)7
[3+2] Cycloadditions of N-Protected ‘(S)-Diazoproline’ with Selected Acetylenes

Grzegorz Mlostoń,* Paulina Pipiak, and Heinz Heimgartner*

*Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland


Acetylene carboxylates and an acetylene phosphonate reacted with N-protected (S)-2-(diazoacetyl)pyrrolidines ((S)-diazoprolines) to give optically active bis-heterocyclic pyrazole derivatives in a regioselective [3+2] cycloaddition. The reactions occurred at 60 °C in THF solution in the absence of a catalyst. However, diethyl ethynylphosphonate reacted significantly slower than the carboxylates. The obtained products were shown to exist in CDCl3 solution at room temperature as mixtures of rotamers. The reactions of diethyl ethynylphosphonate with a selected cyclic α-oxodiazo compound, i.e. 2-diazoacenaphthen-1-one, yielded a fused tricyclic pyrazole derivative.