Asymmetric electrophilic methoxyselenenylations and cyclizations with 3-camphorseleno derivatives

A series of novel 3-camphor-based diselenides, differing in substitution at C-2, was prepared. The corresponding allyl selenides were used as protecting groups for the diselenide moieties in several subsequent transformations. The diastereoselective methoxyselenenylation of alkenes was achieved with methanolic selenenyl triflates derived from the camphor diselenides, of which the 2-keto analogue proved the most effective. Diastereoselective electrophilic cyclizations of unsaturated alcohols, carboxylic acids and amides were most effectively performed with the corresponding selenenyl chloride, containing a spiro-oxazolidinone moiety at C-2 of the camphor residue. The absolute configurations of several products were determined by reductive deselenization. (C) 1999 Elsevier Science Ltd. All rights reserved.