Effects of Methyl Substituents on the Activity and Enantioselectivity of Homobenzotetramisole-Based Catalysts in the Kinetic Resolution of Alcohols
作者:Yuhua Zhang、Vladimir B. Birman
DOI:10.1002/adsc.200900383
日期:2009.10
Substitution of the tetrahydropyrimidine ring in enantioselective acyl transfer catalyst homobenzotetramisole (HBTM) 6 with methyl groups exerts a dramatic influence on its performance in the kineticresolution of secondary alcohols. Syn-3-Methyl analogue of HBTM (9a) has proved to be superior to the parent compound in terms of catalytic activity, enantioselectivity, and synthetic accessibility.
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.
One-Pot Organocatalytic Direct Asymmetric Synthesis of γ-Amino Alcohol Derivatives
作者:Armando Córdova
DOI:10.1055/s-2003-41423
日期:——
This report describes the unprecedented use of unmodified aldehydes as donors in catalytic three component one-pot asymmetric Mannich reactions. The Mannich-type reactions were also readily performed for the first time with both in situ generated and preformed N-PMP protected aromatic aldimines. The proline-catalyzed reactions provided an efficient and very mild entry to either enantiomer of γ-amino alcohol derivatives in high yield and stereoselectivity.
The present invention relates to a process for the deprotection of protected amine compounds, wherein the protected amine compound is contacted with an electrophilic oxidating agent that is optionally formed in situ, said electrophilic oxidating agent being selected from the group of I
2
, Br
2
, Cl
2
and compounds comprising a halogen atom having a formal oxidation state of 1+, 3+, 5+ or 7+, provided that the electrophilic oxidating agent is not iodobenzene diacetate. The process can be conveniently employed in the synthesis of 1,3-amino alcohols, β-amino acids and heterocyclic compounds, in particular β-amino acids.
Enantiomerically pure beta-aminoalcohols, produced through an organocatalytic Mannichreaction, were subjected to an Ugi multicomponent reaction under classical or Lewis acid-promoted conditions with diastereoselectivities ranging from moderate to good. This approach represents a step-economical path to enantiomerically pure, polyfunctionalized peptidomimetics endowed with three stereogenic centers