Solid-Supported 2-Imidazolidinone Chiral Auxiliary for Alkylation

Significance

A solid-phase asymmetric alkylation reaction was described. Thus, the solid-supported 2-imidazolidinone chiral auxiliary 2 was prepared from O-benzyl-l-tyrosine and Wang resin in five steps. Treatment of 2 with acyl chlorides afforded acylated resins 3 in quantitative yield. Asymmetric alkylations of 3 with alkyl halides gave the corresponding alkylated resins 4 in 30-40% yield with >99% de (four examples). The hydrolysis of 4 with NaOH-dioxane (1:1) afforded the α-substituted carboxylic acids 5 (20-30% yield from 2, 89-95% purity, >99% ee) with recovery of 2.