The asymmetricring‐opening/cyclization of cyclopropyl ketones with primary amine nucleophiles was catalyzed by a chiral N,N′‐dioxide/scandium(III) complex through a kinetic resolution process. A broad range of cyclopropyl ketones and primary amines are suitable substrates of this reaction. The corresponding products were afforded in excellent enantioselectivities and yields (up to 97 % ee and 98 %
Asymmetric Ring Opening/Cyclization/Retro-Mannich Reaction of Cyclopropyl Ketones with Aryl 1,2-Diamines for the Synthesis of Benzimidazole Derivatives
reaction of cyclopropyl ketones with aryl 1,2‐diamines has been realized using a chiral N,N′‐dioxide/ScIII catalyst. Benzimidazoles containing chiralsidechains were generated under mild reaction conditions in excellent outcomes (up to 99 % yield and 97 % ee). This method also provides efficient access to chiral benzimidazole‐substituted amide and cycloheptene derivatives.
Synthesis of Chromones from 1,1-Diacylcyclopropanes: Toward the Synthesis of Bromophycoic Acid E
作者:Robert J. Smith、Duong Nhu、Mitchell R. Clark、Sinan Gai、Nigel T. Lucas、Bill C. Hawkins
DOI:10.1021/acs.joc.7b00648
日期:2017.5.19
A tandem deprotection–cyclization reaction of 1,1-diacylcyclopropanes is described which allows rapid access to structurally diverse 2,3-disubstituted chromones in good yields, and with straightforward purification. The utility of this reaction is showcased by the construction of the potent antibacterial marine natural product bromophycoic acid E scaffold.
Polystyrene‐Supported Amino Acids as Efficient Catalyst for Chemical Fixation of Carbon Dioxide
作者:Chaorong Qi、Jinwu Ye、Wei Zeng、Huanfeng Jiang
DOI:10.1002/adsc.201000261
日期:2010.10.9
polystyrene-supported aminoacids have been synthesized and applied to the chemicalfixation of carbondioxide for the first time. Two series of experiments with polystyrene-supported threonine (PS-Thr) and polystyrene-supported tyrosine (PS-Tyr) as catalyst, respectively, were conducted to study the effect of the reaction conditions on the carboxylation of propylene oxide/carbondioxide. There was no considerable