Rhenium Compounds in Organic Synthesis

Abstract

Application of rhenium complexes to organic synthesis has progressed rapidly in 1990's. In this review are summarized the recent advances in synthetic reactions catalyzed or promoted by rhenium complexes. In the first half were described the reactions with high valent rhenium-oxo species. Methyltrioxorhenium catalytically promotes the oxidation of olefins, aromatic rings, and hetero atoms with hydrogen peroxide. The combined use of tetrabutylammonium perrhenate and a Brønsted acid catalyzes the 1,3-rearrangement of allylic alcohols, the Beckmann rearrangement, and the cyclization of benzylacetone oxime derivatives. In the latter half, low valent rhenium-catalyzed reactions were summarized. A chiral rhenium cationic compound readily forms the complexes with olefins and carbonyl compounds in high en antiofacial selectivity. The asymmetric hydrocyanation of aldehydes and the alkylation of quinolines or isoquinolines are developed by diastereoselective addition of nucleophiles to these chiral complexes. Bromopentacarbonylrhenium acts as an efficient Lewis acid, realizing the catalytic Friedel-Crafts acylation of arenes with acyl chloride.