One-Pot Synthesis of α-Amino Acids from CO<sub>2</sub> Using a Bismetal Reagent with Si–B Bond
作者:Tsuyoshi Mita、Jianyang Chen、Masumi Sugawara、Yoshihiro Sato
DOI:10.1021/ol302952r
日期:2012.12.21
TsOH·H2O, precursors of N-Boc-imines can be converted into the corresponding α-aryl or α-alkenyl glycine derivatives under gaseous CO2 in moderate-to-high yields with a single operation. α-Isobutenyl glycine thus obtained can be further derivatized into various types of α-aminoacids including N-Boc-leucine, serine, and glycine derivatives in short steps.
L-tert-Leucine derived urea-ammonium salts: Efficient bifunctional phase transfer catalysts for highly diastereo- and enantioselective aza-Henry reaction of isatin-derived N-Boc ketimines with α-aryl nitromethanes
efficient way of aza-Henry reaction between isatin-derived N-Boc ketimines and α-aryl nitromethanes catalyzed by bifunctional phase transfer catalysts with a quaternary ammonium center derived from L-tert-Leucine has been developed. A series of 3-substituted 3-amino-oxindoles were constructed by this catalytic protocol in excellent yields (90–99%), with high enantioselectivities (83–95%) and diastereoselectivities
Bifunctional asymmetric phase-transfercatalysts bearing multiple hydrogen-bonding donors have rarely been explored. The first quaternary ammonium type of these catalysts derived from cinchona alkaloids were readily prepared and found to be highly efficient catalysts for asymmetric nitro-Mannichreactions of amidosulfones. Compared with previous reports, very broad substrate generality was observed
An efficient enantioselective vinylogous Mannichreaction of N-Boc aminosulfones with noncyclic α,α-dicyanoolefins has been realized using an extraordinary bifunctional thiourea–ammonium salt phase transfer catalyst derived from quinine. A variety of N-Boc aminosulfones and α,α-dicyanoolefins were investigated, and the corresponding products were obtained in excellent yields (up to 99% yield) with
N -Boc氨基砜与非环状α,α-二氰基烯烃的高效对映选择性乙烯基类Mannich反应已使用衍生自奎宁的非常规双官能硫脲-铵盐相转移催化剂实现。研究了各种N -Boc氨基砜和α,α-二氰基烯烃,并以优异的收率(最高99%的收率)和优异的对映选择性(最高ee的98%)获得了相应的产物。所需产物可以容易地转化成有价值的氨基酮。
作者:Xianxing Jiang、Yifu Zhang、Lipeng Wu、Gen Zhang、Xing Liu、Hailong Zhang、Dan Fu、Rui Wang
DOI:10.1002/adsc.200900413
日期:2009.9
doubly stereocontrolled organocatalytic aza-Henry reaction of nitroalkanes to N-Boc-imines generated in situfrom a variety of substituted α-amidosulfones was investigated for the first time, in general, affording the corresponding products with high to excellent yields (up to 93% yield) and enantioselectivities (up to 98% ee), and satisfactory diastereoselectivies (anti/syn up to 98:2). Furthermore