Stereoselective Synthesis of α,α′‐Spirane‐Bridged Dibenzyl Ligands

Abstract

Benzylation in the α,α′‐positions in the benzospirane, 2,2′‐spirobiindane in a cis,cis manner has been effected from the corresponding diketone. Initial Grignard reactions and subsequent water elimination provided a stereoisomeric mixture of α,α′‐alkylidene intermediates, which were stereoselectively hydrogenated to cis,cis‐dibenzyl derivatives. The structure of intermediates in the reaction sequence has been ascertained by X‐ray analyses.

Keywords:

• α,α′‐cis,cis‐Dibenzylspiranes
• α,α′‐disubstituted 2,2′‐bisindanes
• spirane bridge
• stereoselective hydrogenation