A direct catalytic asymmetric vinylogous Mannich-typereaction has been disclosed in good yield, excellent regio-, diastereo- and enantioselectivity. The key to control the regioselectivity is the combination of a bulky N-acylpyrazole and a bulky bisphosphine ligand. The catalytic system was extended to a bisvinylogous Mannich-typereaction by changing the ligand. The synthetic utility of the vinylogous
A Designer Axially Chiral Amino Sulfonamide as an Efficient Organocatalyst for Direct Asymmetric Mannich Reactions of N-Boc-Protected Imines
作者:Taichi Kano、Yukako Yamaguchi、Keiji Maruoka
DOI:10.1002/anie.200805628
日期:2009.2.23
The moderate nucleophilicity of the axiallychiralaminosulfonamide (S)‐1 suppresses the problematic side reactions, including aldol reactions, in the asymmetricMannichreaction of N‐Boc‐protected imines with aldehydes. The corresponding adducts are obtained in good yield and excellent stereoselectivity (see scheme; Boc=tert‐butoxycarbonyl, Tf=trifluoromethanesulfonyl).
anti- and enantioselective aza-Petasis-Ferrier (APF) rearrangement of hemiaminal vinyl ethers catalyzed by a chiral phosphoricacid was investigated by undertaking experimental and theoretical studies. The APF rearrangement is characterized by the following unique mechanistic features: (i) efficient optical kinetic resolution of the starting racemic hemiaminal vinyl ether, (ii) enantioconvergent process