Pictet-Spengler reaction 530 Subject

An efficient method for the oxidative cleavage of solid-supported peptide olefins into aldehydes using a combination of OsOa/NalOa/DABCO system was described by Meldal and coworkers. The resulting aldehydes are subjected to intermolec-ular (V-acylium Pictet-Spengler reactions to furnish pyrroloiso-quinoline derivatives in high purity (eq 76). ... 

STR has recently been applied effectively to catalyze Pictet—Spengler reactions, making this enzyme an attractive subject for extensive studies of application in the drug industry. In the last 20 years, several application strategies have been proposed and studied for STR, which are considered to be a powerful complement for batch alkaloid synthesis and compound library construction. These strategies are summarized in Figure 40. 

On another front, the mixture of allylic alcohols 512 and 513 was converted by reaction with methanesulfonic acid anhydride in the presence of triethylamine to a mixture of the corresponding mesylates, which were subjected collectively to methanolysis to afford 514, and none of the allylic ether epimeric at C-3 was isolated. N Debenzylation of 514 followed by a classic Pictet-Spengler cyclization then afforded ( )-buphanisine (361) (208). 

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