HETEROCYCLES

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: purchase@heterocycles.com

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

■ Synthesis of de novo Chiral γ-Amino-ynamides Using Lithiated Ynamides. Observation of a Unique 5-endo-dig Cyclization with an Inversion of S-Center

Xiao-Na Wang, Richard P. Hsung,* Sierra K. Fox, Ming-Can Lv, and Rui Qi

*Department of Chemistry, School of Pharmacy, University of Wisconsin, 777 Highland Aenue, Madison, WI 53705, U.S.A.

Abstract

We describe herein details of our efforts in developing a highly stereoselective synthesis of de novo chiral γ-amino-ynamides through additions of lithiated ynamides to Ellman–Davis chiral N-tert-butanesulfinyl imines. While additions of ynamides could be highly stereoselective even without Lewis acids, the use of BF3-OEt2 completely reversed the stereoselectivity. On the other hand, additions of oxazolidinone-substituted, oxazinanone-substituted and tetrahydropyrimidinone-substituted ynamides behaved quite differently and functioned better with BF3-OEt2. The chirality of the oxazolidinone ring exerts no impact on the selectivity. This work also features a unique 5-endo-dig cyclization of oxazolidinone-substituted γ-amino-ynamides that could be promoted with acid, leading to isothiazoles and 2,3-dihydro-isothiazole S-oxides.