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[reaction: see text] A highly stereoselective L-proline-catalyzed, asymmetric direct Mannich reaction between a glyoxalate-derived imine and phenyl acetaldehyde was employed for the formation of a syn substituted beta-phenyl homoserine. This Mannich adduct was then readily elaborated to a functionalized beta-phenyl aspartic acid derivative through a series of mild and efficient transformations. 相似文献
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Evans DA Janey JM Magomedov N Tedrow JS 《Angewandte Chemie (International ed. in English)》2001,40(10):1884-1888
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Achiral and chiral 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes were prepared from readily available starting materials. Although more stable than the parent 1-amino-3-siloxy dienes, the 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes are still very reactive in Diels-Alder reactions, somewhat more than 1,3-dialkoxy-1, 3-butadienes (e.g., Danishefsky's diene). The cycloadditions of the achiral and chiral dienes with several different dienophiles were examined. The reactions proceeded in good yield, with modest to high endo selectivity. The chiral dienes exhibited excellent facial selectivity in cycloadditions with alpha-substituted acroleins, maleic anhydride and N-phenylmaleimide. Upon reduction and hydrolysis of the cycloadducts, substituted cyclohexenones were obtained with ee's ranging from 22% to >98%. 相似文献
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In this work we make some contributions to the theory of actions of finite groups on products of spheres. Suppose that the groupZ q r acts freely on the product of k copies of spheres. Question: Isr≤k? We solve this question for several values ofr andk. 相似文献
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Synthesis of Vibegron Enabled by a Ketoreductase Rationally Designed for High pH Dynamic Kinetic Reduction 下载免费PDF全文
Dr. Feng Xu Dr. Birgit Kosjek Dr. Fabien L. Cabirol Dr. Haibin Chen Richard Desmond Dr. Jeonghan Park Anupam P. Gohel Dr. Steven J. Collier Dr. Derek J. Smith Dr. Zhuqing Liu Dr. Jacob M. Janey Dr. John Y. L. Chung Dr. Oscar Alvizo 《Angewandte Chemie (International ed. in English)》2018,57(23):6863-6867
Described here is an efficient stereoselective synthesis of vibegron enabled by an enzymatic dynamic kinetic reduction that proceeds in a high‐pH environment. To overcome enzyme performance limitations under these conditions, a ketoreductase was evolved by a computationally and structurally aided strategy to increase cofactor stability through tighter binding. 相似文献
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Janey JM 《Angewandte Chemie (International ed. in English)》2005,44(28):4292-4300
The direct introduction of either a nitrogen or oxygen atom adjacent to a carbonyl group in a catalytic, enantioselective manner using both chiral Lewis acid and Lewis base catalysis has been described recently. The enantiomerically enriched products of these reactions, such as alpha-amino acids, represent fundamental building blocks for the construction of complex natural products and other important bioactive molecules. This Minireview provides a synopsis of this ever-growing field and highlights some of the challenges that still remain. 相似文献