DirectcatalyticasymmetricMannich-typereactions of gamma-butenolides are described. A chiral Lewis acid/amine base/Bronsted acid combination was used to catalyze a gamma-addition of gamma-butenolides to N-diphenylphosphinoyl imines, affording the products in up to >99% yield, anti/syn = >97:3, and 84% ee. The use of a catalytic amount of TfOH in addition to La(OTf)3/Me-PyBox/TMEDA was important
描述了γ-丁烯内酯的直接催化不对称曼尼希型反应。手性路易斯酸/胺碱/布朗斯台德酸的组合用于催化γ-丁烯内酯向N-二苯基膦酰基亚胺的γ加成反应,从而使产物收率最高> 99%,反/ syn => 97:3,并且84%ee。除La(OTf)3 / Me-PyBox / TMEDA外,还使用催化量的TfOH对于提高收率和立体选择性很重要。
Ba-Catalyzed Direct Mannich-Type Reactions of a β,γ-Unsaturated Ester Providing β-Methyl <i>aza</i>-Morita−Baylis−Hillman-Type Products
Barium-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester are described. The Ba-catalyst not only promoted the Mannich-type reactions, but also isomerizedMannich adducts to afford beta-methyl aza-Morita-Baylis-Hillman-type products in 61-88% yield from various aryl, heteroaryl, and alkyl imines. Preliminary trials on enantioselective variants with a chiral biaryldiol ligand
We report here efficient catalytic imineâimine cross-coupling reactions based on an umpolung strategy; an imine bearing a 9-fluorenyl moiety on its nitrogen atom, which acted as a nucleophile, reacted with another imine to afford an imineâimine cross-coupling adduct in high yield. Furthermore, a chiral guanidine acted as a chiral catalyst for these coupling reactions, and optically active 1,2-diamines were obtained in high yields with high enantioselectivities.