followed by a transmetalation with CuBr⋅P(OEt)3 (−100 °C, 20 s). These stereodefined secondary alkylcoppers underwent stereoretentive cross‐couplings with several 3‐iodo or 3‐bromo unsaturated carbonyl derivatives leading to the corresponding γ‐methylated Michael acceptors in good yields and with high diastereoselectivities (dr up to 96:4). The method was extended to enantiomerically enriched alkylcoppers
手性仲烷基
铜试剂由相应的烷基
碘化物制备,并通过使用t BuLi(-100 °C,1 分钟)进行 I/Li 交换,然后与 CuBr ⋅ P(OEt) 3 (-100 ° C,20 秒)。这些立体定义的仲烷基
铜与几种 3-
碘或 3-
溴不饱和羰基衍
生物进行立体保持交叉偶联,从而以良好的收率和高非对映选择性(dr 高达 96:4)生成相应的 γ-甲基化迈克尔受体。该方法扩展到对映异构体富集的烷基
铜,提供具有高达 90% ee的光学富集的高级
天然产物中间体。