通过使用副念珠菌ATCC 7330的全细胞进行消旋,获得了各种具有芳烃和烷基取代基的光学纯炔丙醇,具有优异的ee(最高> 99%)和分离的收率(最高87%)。整个细胞显示出对烷基取代的底物特异性随着链长的增加,已观察到炔丙醇和对映选择性的变化,从“ R ”变为“ S ”。对映体纯(R)-4-(3-羟基丁-1-炔基)苄腈,(R)-4-(联苯-4-基)丁-3-炔-2-醇,(S)- 3-羟基-5-苯基戊-4-酸乙酯和(S使用该策略获得了)-4-苯基丁-3-炔-1,2-二醇。如此获得的光学纯的炔丙醇用作手性起始原料,成功合成了对映体富集的多取代的吡咯烷和吡咯衍生物,成功地证明了化学酶促路线。
s derived from alkynyl-glycols. The cyclization proceeds selectively to give 4-alkynyl-oxazolines as the propargylic substitution products. Enantioenriched bis-imidates that contain an alkyl or trimethylsilyl substituent at the acetylene gave oxazolines with complete inversion of configuration. In turn, considerable racemization was observed in the cyclization of bis-imidates that contain a phenyl
Chirality Transfer and Asymmetric Catalysis: Two Strategies toward the Enantioselective Formal Total Synthesis of (+)-Gelsenicine
作者:Phil C. Knutson、Haofan Ji、Christopher M. Harrington、Yan-Ting Ke、Eric M. Ferreira
DOI:10.1021/acs.orglett.2c01974
日期:2022.7.15
Two strategies are described en route to an enantioselective total synthesis of gelsenicine. One approach centers on a chirality transfer cycloisomerization that ultimately fell short. Separately, an asymmetric catalysis route utilizing bisphosphine-gold-catalyzed cycloisomerization was pursued. A catalytic system was identified that provided a synthetic intermediate in our Gelsemium alkaloid syntheses