Organocatalytic Knoevenagel condensation by chiral C<sub>2</sub>-symmetric tertiary diamines
作者:Xiaoyu Gu、Yan Tang、Xiang Zhang、Zinbin Luo、Hongfei Lu
DOI:10.1039/c6nj00613b
日期:——
The asymmetric Knoevenagel condensation of aliphatic aldehydes and active methylene compounds catalyzed by (1S,2S)-1,2-diaminocyclohexane-derived catalysts is presented and investigated.
Selective Monoacylation of Symmetrical Diamines via Prior Complexation with Boron
作者:Zhongxing Zhang、Zhiwei Yin、Nicholas A. Meanwell、John F. Kadow、Tao Wang
DOI:10.1021/ol0300773
日期:2003.9.1
[reaction: see text] Pretreatment of a symmetrical primary or secondary diamine with 9-BBN prior to the addition of an acyl chloride significantly suppressed undesired diacylation, and the product of monoacylation predominated. The reactive preference is interpreted as the result of a selective deactivation of one nitrogen atom of the diamine by 9-BBN.
Imidazole-Catalyzed Monoacylation of Symmetrical Diamines
作者:Sanjeev K. Verma、B. N. Acharya、M. P. Kaushik
DOI:10.1021/ol101604q
日期:2010.10.1
An imidazole-catalyzed protocol for monoacylation of symmetricaldiamines has been developed. The protocol gave selective monoacylation of aliphatic (cyclic and acyclic) primary and secondary diamines. In the reaction, imidazole acts as both catalyst and a leaving group. Different monoacylated piperazines and other diamines were synthesized at room temperature in an ethanol/water solvent system.
(S)-(+)-1-Amino-3-phenyloxy-2-propanol, (R)-(−)-2-amino-1-phenylethanol, (S)-(+)-1-amino-2-propanol, (1S,2S)-(+)-2-aminocyclohexanol and (1S,2S)-(+)-1,2-diaminocyclohexane were resolved using dehydroabietic acid. It was shown that good to high enantiomeric purity, between 81∼>99% ee, was obtained and that dehydroabietic acid could be easily and efficiently recovered in a reusable form.
The Unusual Role of CO Transfer in Molybdenum-Catalyzed Asymmetric Alkylations
作者:Shane W. Krska、David L. Hughes、Robert A. Reamer、David J. Mathre、Yongkui Sun、Barry M. Trost
DOI:10.1021/ja028035h
日期:2002.10.1
Spectroscopic and crystallographic studies were undertaken to gain insight into the mechanism of the highly regio- and enantioselective allylic aklylation reaction catalyzed by molybdenum. The chiral ligand (L*) consisting of the mixed benzamide/picolinamide of (S,S,)-trans-1,2-diaminocyclohexane reacts with a typical Mo precatalyst, (norbornadiene)Mo(CO)4, to give a neutral complex L*Mo(CO)4 in which
进行光谱和晶体学研究以深入了解由钼催化的高度区域和对映选择性烯丙基化反应的机制。由 (S,S,)-反式-1,2-二氨基环己烷的混合苯甲酰胺/吡啶甲酰胺组成的手性配体 (L*) 与典型的 Mo 预催化剂 (降冰片二烯)Mo(CO)4 反应,得到中性配合物L*Mo(CO)4,其中配体通过吡啶和相邻的酰胺基团以双齿方式与金属结合。该配合物与肉桂醇的碳酸甲酯反应得到相应的π-烯丙基配合物L*(CO)2Mo(eta3-CH2=CH-CHPh)。该复合物的 NMR 和 X 射线晶体学表征显示,配体通过吡啶氮、相邻酰胺基团的氮以表面封端的三齿方式结合,现在已被去质子化,以及远程酰胺的羰基氧。令人惊讶的是,烯丙基的表面容易受到亲核试剂的攻击,这将导致与催化反应中观察到的立体化学相反的立体化学感。此外,分离形式的烯丙基复合物对丙二酸二甲酯钠没有反应性。然而,在存在一氧化碳源(Mo(CO)6 或气态 CO)的