Chiral allylating reagents, readily generated in situ from tin(II) catecholate [SnII(O2C6H4)], allyl halides, chiral dialkyl tartrates, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), reacted smoothly with aldehydes or reactive ketones at −78 °C in the presence of a catalytic amount of copper salts to afford the corresponding optically active homoallyl alcohols. Allylation of aromatic aldehydes and pyruvates
手性烯丙基化试剂很容易从儿茶酚锡 (II) [SnII(O2C6H4)]、烯丙基卤化物、手性酒石酸二烷基酯和 1,8-二氮杂双环 [5.4.0] undec-7-烯 (DBU) 原位生成,反应平稳在催化量的铜盐存在下,在 -78 °C 下与醛或反应性酮反应,得到相应的光学活性高烯丙醇。本手性锡试剂对芳香醛和丙酮酸的烯丙基化反应以高产率 (81-99%) 和高对映选择性 (89-94%ee) 进行。此外,柠檬苹果酸二甲酯的两种对映异构体均由丙酮酸苄酯的烯丙基化产物制备。
Diastereoselective reactions of pyruvates with but-2-enyl organometallic compounds. Stereocontrol at the tertiary carbon centre
The reaction of pyruvates (3) with but-2-enyl-9-borabicyclo[3.3.1]nonane(2a) or its α-silyl and α-stannyl substituted derivatives (10) produced the threo-isomer [(4) or (11), respectively] stereoselectively; the latter reaction was applied to the synthesis of cis-crobarbatic acid(14).