Allylic trialkylstannanes (1) regioselectively react with allylichalides (2) at room temperature under high pressure (10 kbar) to give head-to-tail coupling products (3) in high yields.
Either the α- (3) or γ-amino acid derivatives (4) can be prepared with very high regioselectivity by treating diethyl azodicarboxylate (DEAD) with (i) lithium dienolates themselves (2) in certain cases, (ii) Sn-masked dienolates (5), or (iii) Ge-masked dienolates (6).
Stabilization and activation of dienolates with germanium and tin. Stereo- and regioselective aldol reactions, regioselective coupling reactions, and regioselective synthesis of amino acid derivatives
Although the reaction of dienolate (1) with aldehydes is frequently lacking in regio- and diastereo-selectivity, the γ-tin substituted derivatives (5), easily obtainable from (1), give (3) and (4) diastereoselectively by controlling the reaction conditions.
The palladiumcatalysedcoupling reaction of the tinmaskeddienolate (2) with organic halides takes place at the position substituted by thin, thereby providing a new method for C–C bondformation at the γ-position of dienolates.