<i>Cinchona</i> Alkaloid Catalyzed Sulfa-Michael Addition Reactions Leading to Enantiopure β-Functionalized Cysteines
作者:Arjen C. Breman、Suze E. M. Telderman、Roy P. M. van Santen、Jamie I. Scott、Jan H. van Maarseveen、Steen Ingemann、Henk Hiemstra
DOI:10.1021/acs.joc.5b01660
日期:2015.11.6
Sulfa-Michael additions to α,β-unsaturated N-acylated oxazolidin-2-ones and related α,β-unsaturated α-amino acid derivatives have been enantioselectively catalyzed by Cinchona alkaloids functionalized with a hydrogen bond donating group at the C6′ position. The series of Cinchona alkaloids includes known C6′ (thio)urea and sulfonamide derivatives and several novel species with a benzimidazole, squaramide
α,β-不饱和N-酰化恶唑烷-2-酮和相关α,β-不饱和α-氨基酸衍生物的磺胺-迈克尔加成反应已通过在C6'位上带有氢键供体基团官能化的金鸡纳生物碱对映选择性催化。金鸡纳系列生物碱包括已知的C6'(硫)脲和磺酰胺衍生物,以及在C6'位置带有苯并咪唑,方胺或苯甲酰胺基团的几种新物种。磺酰胺特别适合用作双官能有机催化剂,因为它们使产物具有非常好的非对映选择性和高对映选择性。特别地,C6'磺酰胺催化与α,β-不饱和α-氨基酸衍生物的反应,以高达93:7的非对映体比例提供产物,主要异构体以高达99的ee形成%。随后将有机催化的磺胺-迈克尔加成产物加到α,β-不饱和α-氨基酸衍生物上,以高收率转化为对映体纯的β-官能化半胱氨酸,适用于天然化学连接。