Asymmetric nucleophilic addition to β- and γ-alkoxy aldehydes using carbohydrate as a chiral auxiliary
作者:Tomoyasu Yoshida、Jun-ichi Chika、Hisashi Takei
DOI:10.1016/s0040-4039(98)00717-5
日期:1998.6
The nucleophilicaddition of Grignard reagents and allyltributyltin to chiral ω-tetra-hydropyranyloxy propanal and butanal derived from l-fucose and d-arabinose gave the corresponding alcohols with high diastereoselectivity (up to 51% de by 1, 6-asymmetric induction and 95% de by 1, 5-asymmetric induction).
The 2-Benzyloxytetrahydropyranyl group as a chiral auxiliary for the nucleophilic addition to α-alkoxy aldehydes
作者:André B. Charette、Christophe Mellon、Mehrnoush Motamedi
DOI:10.1016/0040-4039(95)01766-b
日期:1995.11
The addition of Grignard reagent, hydride reagents and crotylstannanes to an α-alkoxy carbonyl bearing the 2-benzyloxytetrahydropyranyl group showed good levels of diastereofacial control. The sense of induction was the same as that reported for the addition of allylSnBu3. An important solvent effect consistent with the proposed transition state model was observed in these reactions.