Reversal of diastereoselectivity of nitrile oxide 1,3-dipolar cycloadditions by Mg(II). Acceleration of cycloaddition by microwave irradiation

摘要

1,3-Dipolar cycloadditions of mesitonitrile oxide to Baylis-Hillman adducts (beta-hydroxy-alpha-methylene esters) proceed regioselectively in good yields. Addition of Grignard reagent reverses the diastereoselectivity of the cycloaddition. Microwave irradiation strongly accelerates the reaction with only a small effect on its diastereoisomeric excess. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 19]