Asymmetric reduction of nitroalkenes with baker's yeast
摘要:
Various alpha,beta -disubstituted and trisubstituted nitroalkenes were chemoselectively reduced with baker's yeast to the corresponding nitroalkanes. Stereoselectivities of the reduction of alpha,beta -disubstituted nitroalkenes were modest to low, and e.e.s up to 52% were obtained. Trisubstituted nitroalkenes could be reduced to the corresponding nitroalkanes with excellent enantioselectivities, moderate diastereoselectivities and in good yield. (C) 2001 Elsevier Science Ltd. All rights reserved.
Asymmetric reduction of nitroalkenes with baker's yeast
摘要:
Various alpha,beta -disubstituted and trisubstituted nitroalkenes were chemoselectively reduced with baker's yeast to the corresponding nitroalkanes. Stereoselectivities of the reduction of alpha,beta -disubstituted nitroalkenes were modest to low, and e.e.s up to 52% were obtained. Trisubstituted nitroalkenes could be reduced to the corresponding nitroalkanes with excellent enantioselectivities, moderate diastereoselectivities and in good yield. (C) 2001 Elsevier Science Ltd. All rights reserved.
Regiodivergent Electrophotocatalytic Aminooxygenation of Aryl Olefins
作者:He Huang、Tristan H. Lambert
DOI:10.1021/jacs.2c08951
日期:2022.10.19
conditions is described. The procedure employs a trisaminocyclopropenium (TAC) ion catalyst with visible light irradiation under a controlled electrochemical potential to convert aryl olefins to the corresponding oxazolines with high chemo- and diastereoselectivity. With the judicious choice between two inexpensive and abundant reagents, namely water and urethane, either 2-amino-1-ol or 1-amino-2-ol derivatives
A formal, two-step anti-Markovnikov addition of H2O to diastereomeric mixtures of trisubstituted olefins towards enantio- and diastereomerically highly-enriched alcohols is demonstrated. This method relies on the syn-specific Shi-epoxidation, followed by a titanocene-catalyzed epoxide hydrosilylation featuring a directional-isomerization step to converge the diastereomeric mixtures of epoxides into
证明了H 2 O 向三取代烯烃的非对映体混合物中向对映体和非对映体高度富集的醇进行正式的两步反马尔可夫尼科夫加成。该方法依赖于顺式特定的Shi环氧化,然后是二茂钛催化的环氧化物氢化硅烷化,其特征在于定向异构化步骤,将环氧化物的非对映异构体混合物聚合成单一立体异构体。
Iodine-Catalyzed Facile Approach to Sulfones Employing TosMIC as a Sulfonylating Agent
A novel iodine-catalyzed functionalization of a variety of olefins and alkynes and direct decarboxylative functionalization of cinnamic and propiolic acids with TosMIC to provide access to various vinyl, allyl, and beta-iodo vinylsulfones is described. This simple, efficient, and environmentally benign approach employing inexpensive molecular iodine as a catalyst demonstrates a versatile protocol for the synthesis of highly valuable sulfones, rendering it attractive to both synthetic and medicinal chemistry.
Highly Enantioselective and <i>Anti</i>-Diastereoselective Catalytic Intermolecular Glyoxylate–Ene Reactions: Effect of the Geometrical Isomers of Alkenes
An efficient method for the synthesis of homoallylic alcohols with high enantioselectivities and anti-diastereoselectivities via an In(III)-catalyzed intermolecular glyoxylateene reaction has been developed. The geometrical isomers of alkenes were shown to have different reactivities. Only the isomers of the alkenes having a proton beta-cis to the substituent reacted in this catalytic system.
Access to “Friedel–Crafts-Restricted” <i>tert</i>-Alkyl Aromatics by Activation/Methylation of Tertiary Benzylic Alcohols
作者:Joshua A. Hartsel、Derek T. Craft、Qiao-Hong Chen、Ming Ma、Paul R. Carlier
DOI:10.1021/jo202371c
日期:2012.4.6
Herein we describe a two-step protocol to prepare m-tert-alkylbenzenes. The appropriate tertiary benzylic alcohols are activated with SOCl2 or concentrated HCl and then treated with trimethylaluminum, affording the desired products in 68-97% yields (22 examples). This reaction sequence is successful in the presence of a variety of functional groups, including acid-sensitive and Lewis-basic groups. In addition to t-Bu groups, 1,1-dimethylpropyl and 1-ethyl-1-methylpropyl groups can also be installed using this method.