Enantioselective Synthesis of Chiral α-Azido and α-Aryloxy Quaternary Stereogenic Centers via the Phase-Transfer-Catalyzed α-Alkylation of α-Bromomalonates, Followed by S<sub>N</sub>2 Substitution
作者:Doyoung Kim、Min Woo Ha、Suckchang Hong、Cheonhyoung Park、Byungsoo Kim、Jewon Yang、Hyeung-geun Park
DOI:10.1021/acs.joc.7b00324
日期:2017.5.5
A new efficient synthetic method for chiral α-azido-α-alkylmalonates and α-aryloxy-α-alkylmalonates was developed. The enantioselective α-alkylation of diphenylmethyl tert-butyl α-bromomalonate under phase-transfer catalytic conditions [(S,S)-3,4,5-trifluorophenyl-NAS bromide, 50% KOH, toluene, and −40 °C) provided the corresponding α-bromo-α-alkylmalonates in high chemical yields (≤98%) and high optical
开发了一种新的手性α-叠氮基-α-烷基丙二酸酯和α-芳氧基-α-烷基丙二酸酯的合成方法。提供了在相转移催化条件下[(S,S)-3,4,5-三氟苯基-NAS溴化物,50%KOH,甲苯和-40°C)的二苯基甲基α-溴丙二酸叔丁基叔丁酯的对映选择性α-烷基化相应的α-溴-α-烷基丙二酸酯的化学产率高(≤98%),光学产率高(ee≤99%)。通过用N 2取代S N 2 ,将所得的α-烷基化产物转化为α-叠氮基-α-烷基丙二酸酯(≤96%,≤97%ee)和α-芳氧基-α-烷基丙二酸酯(≤79%,≤93%ee)。叠氮化钠和芳基氧化物。
Enantioselective Synthesis of Chiral α-Thio-Quaternary Stereogenic Centers via Phase-Transfer-Catalyzed α-Alkylation of α-Acylthiomalonates
作者:Min Woo Ha、Jun Young Lee、Doyoung Kim、Geumwoo Lee、Jae Kyun Lee、Suckchang Hong、Hyeung-geun Park
DOI:10.1021/acs.joc.7b02605
日期:2018.1.19
An efficient synthetic method for establishing chiral α-thio-α-quaternary stereogenic center was successfully developed. The enantioselective α-alkylation of α-acylthiomalonates under phase-transfer catalytic conditions [50% aq. KOH, toluene, −20 °C, and (S,S)-3,4,5-trifluorophenyl-NAS bromide] provided the corresponding α-acylthio-α-alkylmalonates in high chemical yields (up to 99%) and high optical
A new enantioselective synthetic method for α-halo-α-alkylmalonates is reported. α-Alkylation of diphenylmethyl tert-butyl α-halomalonates under phase-transfer catalytic conditions (solid KOH, toluene, −40 °C) in the presence of (S,S)-3,4,5-trifluorophenyl-NAS bromide (5 mol%) afforded diphenylmethyl tert-butyl α-halo-α-alkylmalonates in very high chemical yields (up to 99%) and optical yields (up