Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation
作者:Yang Liu、Julie Oble、Giovanni Poli
DOI:10.3762/bjoc.15.107
日期:——
complementary [3 + 2] annulation protocols between 3-oxoglutarates and cyclic γ-oxy-2-cycloalkenones, simply differing on the reaction temperature, are disclosed. These domino transformations allow C-C/O-C or C-C/C-C [3 + 2] annulations at will, via an intermolecular Pd-catalyzed C-allylation/intramolecular O- or C-1,4-addition sequence, respectively. In particular, exploiting the reversibility of the O-1
公开了在3-氧戊二酸酯和环状γ-氧基-2-环烯酮之间的两个互补的[3 + 2]环合方案,只是反应温度不同。这些多米诺骨转化可以分别通过分子间Pd催化的C-烯丙基化/分子内O-或C-1,4-加成序列随意进行CC / OC或CC / CC [3 + 2]脱环。特别是,利用O-1,4-加成步骤的可逆性,结合不可逆的C-1,4-加成/脱羧途径,分子内共轭物加成步骤可以从动力学(O-烷基化)转移到由于简单的温度升高,热力学路径(C-烷基化)成为可能。这种双亲核试剂/双亲电子试剂[3 + 2]的成功成功的关键是其明确定义的步骤时间顺序以及前一步的总化学选择性。这种[3 + 2] CC / OC键形成环的协议也可以扩展到1,3,5-三酮以及1,3-双磺酰基丙烷-2-酮双亲核试剂。