133420-97-0Relevant academic research and scientific papers
Enantioselective protonation of α-hetero carboxylic acid-derived ketene disilyl acetals under chiral ionic Bronsted acid catalysis
Uraguchi, Daisuke,Kizu, Tomohito,Ohira, Yuki,Ooi, Takashi
supporting information, p. 13489 - 13491 (2015/01/09)
Highly enantioselective protonation of α-halo and alkoxy carboxylic acid-derived ketene disilyl acetals is achieved by using P-spiro chiral diaminodioxaphosphonium barfate as a Bronsted acid catalyst, where the enantiofacial discrimination by the catalyst mainly stems from the recognition of the electronic difference between two substituents on the ketene disilyl acetal.
Enantioselective iron-catalysed O-H bond insertions
Zhu, Shou-Fei,Cai, Yan,Mao, Hong-Xiang,Xie, Jian-Hua,Zhou, Qi-Lin
experimental part, p. 546 - 551 (2010/10/04)
The ready availability, low price and environmentally benign character of iron mean that it is an ideal alternative to precious metals in catalysis. Recent growth in the number of iron-catalysed reactions reported reflects an increasing demand for sustainable chemistry. Only a limited number of chiral iron catalysts have been reported and these have, in general, proven less enantioselective than other transition-metal catalysts, thus limiting their appeal. Here, we report that iron complexes of spiro-bisoxazoline ligands are highly efficient catalysts for asymmetric O-H bond insertion reactions. These complexes catalyse insertions into the O-H bond of a wide variety of alcohols and even water, with exceptional enantioselectivities under mild reaction conditions. The selectivities surpass those obtained with other transition-metal catalysts. This study should inspire and encourage the use of iron instead of traditional precious metals in the development of greener catalysts for catalytic asymmetric synthesis.
Stereoselective functionalisation of SuperQuat enamides: asymmetric synthesis of homochiral 1,2-diols and α-benzyloxy carbonyl compounds
Aciro, Caroline,Davies, Stephen G.,Garner, A. Christopher,Ishii, Yutaka,Key, Min-Suk,Ling, Kenneth B.,Prasad, R. Shyam,Roberts, Paul M.,Rodriguez-Solla, Humberto,O'Leary-Steele, Catherine,Russell, Angela J.,Sanganee, Hitesh J.,Savory, Edward D.,Smith, Andrew D.,Thomson, James E.
, p. 9320 - 9344 (2008/12/22)
Homochiral (E)- and (Z)-enamides derived from SuperQuat (S)-4-phenyl-5,5-dimethyl-oxazolidin-2-one undergo highly diastereoselective epoxidation upon treatment with dimethyldioxirane. Subsequent epoxide opening with meta-chlorobenzoic acid proceeds via a stereoselective SN1-type process, with retention of configuration, to give the corresponding 1′-m-chlorobenzoyl-2′-hydroxy derivatives. Treatment of the SuperQuat enamides with mCPBA effects this two-step transformation in one pot. Reductive cleavage of the isolated 1′-m-chlorobenzoyl-2′-hydroxy derivatives (≥96% de) generates homochiral 1,2-diols in ≥96% ee. Alternatively, regioselective lithiation of the enamide at C(1′) with tBuLi followed by reaction with an aromatic aldehyde and in situ O-benzylation generates a 1′-(benzyloxy-aryl-methyl) substituted enamide with high diastereoselectivity. Subsequent oxidative cleavage of the enamide C{double bond, long}C bond with NaIO4/RuCl3 followed by methanolysis of the resultant N-acyl fragment furnishes an O-benzyl protected α-hydroxy methyl ester in high ee.
A new approach for the determination of the absolute configuration of secondary alcohols by 1H NMR with O-substituted mandelate derivatives
Chataigner, Isabelle,Lebreton, Jacques,Durand, Didier,Guingant, Andre,Villieras, Jean
, p. 1759 - 1762 (2007/10/03)
It is shown that the cheap and easily prepared mandelic acid esters (or their OAc analogues) are best suited than the expensive, although usually employed. OMe mandelic acid esters to assess both the enantiomeric excesses and absolute configurations of se
Synthesis of O-Protected (R)-2-Hydroxy Aldehyde and Their Hydrocyanation
Effenberger, Franz,Hopf, Martin,Ziegler, Thomas,Hudelmayer, Jochen
, p. 1651 - 1659 (2007/10/02)
The synthesis of O-silyl- and O-benzyl-protected (R)-2-hydroxy aldehydes (R)-6 from (R)-2-hydroxy carboxylic acids (R)-1 is described.While attempts for their diastereoselective hydrocyanation with hydrocyanic acid and (R)-oxynitrilase as catalyst have not been successful, the cyano silylation with trimethylsilyl cyanide occurred diastereoselectively with a ratio of 81:19 preferring the threo form without racemization at C-2 of the 2-hydroxy aldehyde. Key Words : (R)-2-Hydroxy aldehydes, O-protected / Hydrocyanation
