ENOL THIOETHERS AS ENOL SUBSTITUTES. AN ALKYLATION SEQUENCE.

Article abstract of DOI:10.1021/ja00353a037

Ionic bromination of enol phenyl thiolethers forms predominantly to exclusively 2-(phenylthio)-3-bromo-1-alkenes, an enolonium equivalent. The allylic bromide participates in displacements with stabilized and nonstabilized nucleophiles. The ability to hydrolyze the enol thioethers to their corresponding ketones equates this sequence to an equivalence of an enolonium ion. The versatility of the sulfur in selective introduction of allylic hydroxyl and amino groups as well as the ability to directly replace the sulfur substituent by hydrogen or alkyl imparts special significance to this approach. The sequence is highly regio-and chemoselective. Applications include the synthesis of lanceol and bisabolene and the introduction of steroid side chains.