Regioselective synthesis of substituted pterocarpans and pterocarpenes. Lewis acid Ti (IV) promoted formal (3+2) cycloaddition reactions.
作者:Modachur G. Murugesh、Kandasamy Subburaj、Girish K. Trivedi
DOI:10.1016/0040-4020(95)01052-1
日期:1996.2
A synthesis of novel pterocarpans (8a–e, 10a–c and 11a–e) and pterocarpenes (7a–d and 9a–c) has been carried out. This method involves the Lewis acid Ti (IV) promoted formal (3+2) cycloaddition reaction of 2-alkoxy-1,4-benzoquinones (6a–c) with appropriately substituted 2H-chromenes (1a–b, 2a–b and 5) at −78°C.
ZnCl<sub>2</sub>Promoted Formal (3+2) Cycloaddition Reactions of 2-Alkoxy-1,4-benzoquinones with 2<i>H</i>-Chromenes
作者:Kandasamy Subburaj、Modachur G. Murugesh、Girish K. Trivedi
DOI:10.1080/00397919608005223
日期:1996.8
Abstract A simple, mild, inexpensive and highly efficient method for the synthesis of 2,2-dimethyldihydropyranopterocarpans (4a–h and 5a–b) by formal (3+2) cycloadditionreactions of 2-alkoxy-1,4-benzoquinones (3a–b) with 2H-chromenes (1a–d and 2) using ZnCl2 at room temperature has been developed.