The first direct asymmetricvinylogousMannich (AVM) reaction of alpha,alpha-dicyanoolefins and N-Boc aldimines was described promoted by a simple chiral bifunctional thiourea-tertairy amine organocatalyst. The reaction was highlyefficient (S/C up to 1000) and regio-, stereoselective (generally >99% de, 96 to >99.5% ee) at room temperature for a broad array of substrates. Enantiomerically pure delta-amino
The first asymmetric Mannich-type reaction of stabilized phosphorus ylides and N-Boc aldimines was described promoted by a readily available and recyclable chiral bisthiourea organocatalyst. Subsequent reaction with formalin smoothly provides N-Boc-β-amino-α-methylene carboxylic esters in a highlyenantiomericallyenriched form (up to 96% ee).
Asymmetric Aza-Morita-Baylis-Hillman Reactions of Alkyl Vinyl Ketones with N-Protected Imines or In Situ Generated N-Protected Imines
作者:Xiao-Yang Guan、Yin Wei、Min Shi
DOI:10.1002/ejoc.201000496
日期:2010.7
DABCO-catalyzed aza-MBH reactions of N-Boc imines with MVK and EVK have been thoroughly investigated in the paper. The asymmetric version of this aza-MBH reaction was also systematically investigated by using a chiral amine or a chiral phosphane catalyst. It was found that most of the N-protected imines are suitable substrates under the mild reaction conditions and are able to give the corresponding
DABCO 催化的 N-Boc 亚胺与 MVK 和 EVK 的 aza-MBH 反应已在论文中进行了彻底的研究。还通过使用手性胺或手性磷烷催化剂系统地研究了这种 aza-MBH 反应的不对称形式。发现大多数 N 保护的亚胺在温和的反应条件下是合适的底物,并且能够以中等产率和高 ee 值得到相应的加合物。TQO-或LB1-催化的N-保护的α-酰氨基烷基苯砜或α-酰氨基烷基对甲苯基砜与MVK的氮杂-MBH反应可以很好地进行,这为获得高对映选择性氮杂-MBH加合物提供了一种简便直接的途径.
Enantioselective Aza-Henry Reaction with an <i>N</i>-Sulfinyl Urea Organocatalyst
作者:MaryAnn T. Robak、Monica Trincado、Jonathan A. Ellman
DOI:10.1021/ja075653v
日期:2007.12.1
simultaneously acidify the urea and provide asymmetric induction in hydrogen-bond-catalyzed reactions. The utility of this new catalyst structure is demonstrated by the high selectivity provided in the aza-Henryreaction not only for aromatic N-Boc imine substrates but also for aliphatic imines for which enantioselective H-bonding catalysis has not previously been demonstrated.
Chiral N-Heterocyclic Carbene Catalyzed Staudinger Reaction of Ketenes with Imines: Highly Enantioselective Synthesis of <i>N</i>-Boc β-Lactams
作者:Yan-Rong Zhang、Lin He、Xu Wu、Pan-Lin Shao、Song Ye
DOI:10.1021/ol702759b
日期:2008.1.1
N-heterocycliccarbenes (NHCs) were demonstrated to be efficient catalysts for the Staudinger reaction of ketenes with N-tosyl, N-benzyloxycarbonyl, or N-tert-butoxycarbonyl imines. Chiral NHC 8b, conveniently prepared from L-pyroglutamic acid, catalyzed the reactions of arylalkylketenes with a variety of N-tert-butoxycarbonyl arylimines to give the corresponding cis-beta-lactams in good yields with