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

Article abstract of DOI:10.1016/j.tetlet.2005.10.015

A straightforward synthesis of (±)-coerulescine and (±)-horsfiline has been established from 3-formyl-3-phenylpyrrolidine 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- phenylpyrrolidine to the 3,3-spirocyclic 2-oxindole ring skeleton.