The oxa-Pictet-Spengler reaction: A highlight on the different efficiency between isochroman and phthalan or homoisochroman derivative syntheses

摘要

Recently we reported that 6-hydroxy- and 6,7-dihydroxyisochromans can be obtained under very mild conditions and with very good yield by a one-pot synthesis based on a modified oxa-Pictet-Spengler reaction. In this paper, we demonstrate that the above reaction is also useful for the synthesis of hydroxyphthalans, and we discuss the effects of the substituents on the alcoholic aromatic ring on the course of the reaction, as well as those on the aldehydic structure. We also report a synthesis of hydroxyhomoisochromans performed by the same method.