The Direct, Enantioselective, One-Pot, Three-Component, Cross-Mannich Reaction of Aldehydes: The Reason for the Higher Reactivity of Aldimineversus Aldehyde in Proline-Mediated Mannich and Aldol Reactions
In the proline-mediatedMannich and aldolreactions of propanal as a nucleophile, the aldimine prepared from benzaldehyde and p-anisidine is about 7 times more reactive than the corresponding aldehyde, benzaldehyde, as an electrophile. This higherreactivity of aldimine over aldehyde is attributed to the carboxylic acid of proline protonating the basic nitrogen atom of the aldimine more effectively
The Direct Catalytic Asymmetric Cross-Mannich Reaction: A Highly Enantioselective Route to 3-Amino Alcohols andα-Amino Acid Derivatives
作者:Armando Córdova
DOI:10.1002/chem.200305646
日期:2004.4.19
The first proline-catalyzed direct catalytic asymmetricone-pot, three-component cross-Mannich reaction has been developed. The highly chemoselective reactions between two different unmodified aldehydes and one aromatic amine are new routes to 3-amino aldehydes with dr>19:1 and up to >99 % ee. The asymmetric cross-Mannich reactions are highly syn-selective and in several cases the two new carbon centers
作者:Jorge M. M. Verkade、Lieke J. C. van Hemert、Peter J. L. M. Quaedflieg、Hans E. Schoemaker、Martin Schürmann、Floris L. van Delft、Floris P. J. T. Rutjes
DOI:10.1002/adsc.200700060
日期:2007.6.4
A novel enzymatic procedure for the oxidative deprotection of p-methoxyphenyl (PMP)-protectedamines is described. By using laccases (E.C. 1.10.3.2) under mildly acidic conditions, a variety of PMP-protected amines were successfully deprotected. The rate of deprotection was solvent- and pH-dependent, and the reaction scope could be increased by using so-called mediators.
The Direct Organocatalytic Asymmetric Mannich Reaction: Unmodified Aldehydes as Nucleophiles
作者:Wolfgang Notz、Fujie Tanaka、Shin-ichi Watanabe、Naidu S. Chowdari、James M. Turner、Rajeswari Thayumanavan、Carlos F. Barbas
DOI:10.1021/jo0347359
日期:2003.12.1
The unprecedented application of unmodified aldehydes as nucleophilic donors in direct catalytic asymmetricMannich-typereactions is disclosed in a full account. Our efforts in broadening the applicability of chiral pyrrolidine-based catalysts in direct asymmetricMannich-typereactions led to the highly diastereo- and enantioselective and concise synthesis of functionalized alpha- and beta-amino
A concise asymmetricsynthesis of disubstituted N-heterocycles is reported. Our approach utilizes an optimized Mannich reaction of functionalized aldehydes, followed by a novel dehydrative cyclization mediated by the Staab reagent (1,1'-carbonyldiimidazole, CDI). The method was applied to the synthesis of azetidines, piperidines and pyrrolidines.