Synthesis of (+-)-coerulescine and a formal synthesis of (+-)-horsfiline

摘要

A straightforward synthesis of (+-)-coerulescine and (+-)-horsfiline has been established from 3-formyl-3-phenylpyrrol-idine employing 4-hydroxypiperidine as the starting material.There are two remarkable steps for the synthesis of (+-)-coerulescine and (+-)-horsfiline.One is the rapid access to produce 3-formyl-3-phenylpyrrolidine by Lewis acid-catalyzed rearrangement of 3,4-dihydroxy-4-phenylpiperidine.The other key step is an intramolecular electrophilic cyclization from 3-benzylcarbamoyl-3-phenyl-pyrrolidine to the 3,3-spirocyclic 2-oxindole ring skeleton.