Gleason-type chiralauxiliaries were used for the synthesis of a novel class of sulfonium salts, obtained via methylation of the sulfide with Meerwein's salt. The salts were reacted with aldehydes under basic conditions to provide epoxy amides, which were reduced to their corresponding epoxy alcohols in excellent enantiomeric excesses. Interestingly, it was feasible to synthesize both enantiomeric
Asymmetric Epoxidation of α,β-Unsaturated Aldehydes in Aqueous Media Catalyzed by Resin-Supported Peptide- Containing Unnatural Amino Acids
作者:Kengo Akagawa、Kazuaki Kudo
DOI:10.1002/adsc.201000805
日期:2011.4.18
The enantio‐ and diastereoselective epoxidation of α,β‐unsaturated aldehydes in aqueousmedia was realized using a resin‐supported peptide catalyst. Introducing the hydrophobic and bulky unnaturalaminoacid 3‐(1‐pyrenyl)alanine into the peptide sequence was effective for enhancing the reaction rate and enantioselectivity.
Reaction of epoxides with [n-Bu3SnAlMe3]−Li+ affords β-oxido stannanes which collapse to alkene with overall retention of stereochemistry. The SN2 type ring opening of epoxides by tributylstannyl anion followed by anti elimination of Bu3Sn and OAl−Me3 groups explains the stereochemical results. The method can be successfully applied to hydroxy epoxides derived from (E)-2-nonen-1-ol. The deoxygenation of epoxides
Tungsten-Catalyzed Regio- and Enantioselective Aminolysis of<i>trans</i>-2,3-Epoxy Alcohols: An Entry to Virtually Enantiopure Amino Alcohols
作者:Chuan Wang、Hisashi Yamamoto
DOI:10.1002/anie.201408732
日期:2014.12.8
The first catalytic enantioselectiveaminolysis of trans‐2,3‐epoxy alcohols has been accomplished. This stereospecific ring‐opening process was efficiently promoted by a tungsten/bis(hydroxamic acid) catalytic system, furnishing various anti‐3‐amino‐1,2‐diols with excellent regiocontrol and high enantioselectivities (up to 95 % ee). Moreover, virtually enantiopure 3‐amino‐1,2‐diols could be obtained
A convenient synthesis of aziridine-2-carboxylic esters
作者:Johan Legters、Lambertus Thijs、Binne Zwanenburg
DOI:10.1002/recl.19921110101
日期:——
Optically active oxirane-2-carboxylic esters, prepared from allylic alcohols employing the Sharpless epoxidation, were treated with sodium azide. The azido alcohols obtained were subsequently converted into aziridine-2-carboxylicesters by reaction with triphenylphosphine, in good yields and with high optical purity. Various racemic oxirane-2-carboxylic esters were subjected to the same sequence of