Synthesis of .alpha.-cyano carbonyl compounds by flash vacuum thermolysis of (alkylamino)methylene derivatives of Meldrum's acid. Evidence for facile 1,3-shifts of alkylamino and alkylthio groups in imidoylketene intermediates
摘要:
The syntheses and flash vacuum thermolyses of 5-[(alkylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones (Meldrum's acid derivatives) 13a-i are described. Thermolysis of 13a as well as of ethyl 3-(tert-butylamino)acrylate (22) gives a tautomeric mixture of cyanoacetaldehyde (14) and 3-hydroxypropenenitrile (15). Thermolysis of 13b gives iminoacrolein 26 and not cyanoacetone (29). Thermolysis of 13c,d gives S-methyl cyanothioacetate (30), and 13f-h give cyanoacetamides 31 in high yields. 2-Cyanopent-4-enoic acid derivatives 32 are obtained from Meldrum's acids 13e,i. The results are discussed in terms of facile 1,3-shifts of methylthio and alkylamino groups in imidoylketenes, interconverting imidoylketenes and acylketene imines.
Control of Diastereoselectivity in Tandem Asymmetric Reactions Generating Nonadjacent Stereocenters with Bifunctional Catalysis by Cinchona Alkaloids
作者:Baomin Wang、Fanghui Wu、Yi Wang、Xiaofeng Liu、Li Deng
DOI:10.1021/ja0670409
日期:2007.1.1
We report the manipulation of hydrogen-bonding-based cooperative catalysis to control the diastereoselectivity for a tandem asymmetric reaction creating two nonadjacent stereocenters. This ability to control both the enantioselectivity and diastereoselectivity allows, for the first time, the direct and stereoselective construction of 1,3-tertiary-quaternary stereocenters in any of the possible four configurations from the same prochiral precursors with catalytic control. The synthetic consequence of such catalyst-controlled construction of nonadjacent stereocenters is illustrated by the asymmetric synthesis of manzacidin C by using the same reaction sequence that was previously applied to the total synthesis of manzacidin A.
CHEIKH, ABDELHAMID;BEN;CHUCHE, JOSSELIN;MANISSE, NOEL;POMMELET, JEAN CLAU+, J. ORG. CHEM., 56,(1991) N, C. 970-975
作者:CHEIKH, ABDELHAMID、BEN、CHUCHE, JOSSELIN、MANISSE, NOEL、POMMELET, JEAN CLAU+
DOI:——
日期:——
Asymmetric carbon-carbon-bond-forming reactions catalyzed by bifunctional cinchona alkaloids
申请人:Deng Li
公开号:US20070083049A1
公开(公告)日:2007-04-12
One aspect of the present invention relates to quinine-based and quinidine-based catalysts. In certain embodiments, the quinine-based and quinidine-based catalysts contain a hydroxy group at the 6′ position. In certain embodiments, the quinine-based and quinidine-based catalysts contain an O-aryl group or an O-aroyl group at the C9 position. In certain embodiments, the quinine-based and quinidine-based catalysts contain an optionally substituted O-diazene group or an optionally substituted O-benzoyl group at the C9 position. In certain embodiments, the quinine-based and quinidine-based catalysts contain a thiourea at the C9 position. In certain embodiments, the quinine-based and quinidine-based catalysts contain an NH(═S)NH-aryl group at the C9 position. Another aspect of the present invention relates to a method of preparing a chiral, non-racemic compound from a prochiral electron-deficient alkene or prochiral imine, comprising the step of: reacting a prochiral alkene or imine with a nucleophile in the presence of a catalyst; thereby producing a chiral, non-racemic compound; wherein said catalyst is a derivatized quinine or quinidine. In certain embodiments, the nucleophile is a malonate or β-ketoester. In certain embodiments the nucleophile is an alkyl or aryl or aralkyl 2-cyano-2-alkylacetate. In certain embodiments the nucleophile is an alkyl or aryl or aralkyl 2-cyano-2-alkylacetate. Another aspect of the present invention relates to a method of kinetic resolution, comprising the step of: reacting a racemic aldehyde or racemic ketone with a nucleophile in the presence of a derivatized quinine or quinidine, thereby producing a non-racemic, chiral compound. In certain embodiments, the kinetic resolution is dynamic.