SYNTHESIS OF CHIRAL DEPSIPEPTIDE BUILDING BLOCK VIA ASYMMETRIC HYDROSILYLATION
作者:Jin-shui Yao、You-shi Wu
DOI:10.1081/scc-120002401
日期:2002.1.1
ABSTRACT Asymmetric hydrosilylation of N-(α-ketoacyl)-α-amino esters was performed, catalyzed by rhodium(I) complex of chiral 2-(2-pyridyl)-4-carbomethoxy-1,3-thiazolidine or Rh(PPh3)3Cl. The N-(α-hydroxyacyl)-α-amino esters were synthesized in high stereoselectivity.
Amino acid methyl esters were used as amine nucleophiles in palladium catalysed aminocarbonylation of iodobenzene and iodoalkenes (1-iodo-cyclohexene and 17-iodo-androst-16-ene). 2-Oxo-carboxamide type derivatives can be isolated as a result of double CO insertion by using iodobenzene as a substrate at elevated carbon monoxide pressure. On the contrary, carboxamides of expected structure were obtained exclusively in excellent yields in the whole pressure range by using iodoalkenes. The aminocarbonylation of 17-iodo-androst-16-ene in [bmim][PF6] or [bmim][BF4] (where bmim=1-butyl-3-methyl-imidazolium cation) ionic liquids was also carried out and the ionic liquid-catalyst mixtures have been reused several times with only a small loss of activity. (C) 2004 Elsevier Ltd. All rights reserved.
Visible-light-mediated metal-free decarboxylative acylations of isocyanides with α-oxocarboxylic acids and water leading to α-ketoamides
An efficient visible-light-promoted approach for preparing α-ketoamides from α-oxocarboxylic acids, isocyanides and water is disclosed. The present transformation could be achieved under mild and metal-free conditions through a sequence of decarboxylation, radical addition and hydration processes, which provides a novel and facile route to construct α-ketoamides from simple and readily available chemical
Reversible Diastereoselective Photocyclization of Phenylglyoxylamides of α-Amino Acid Methyl Esters to 3-Hydroxy β-Lactams
作者:Axel G. Griesbeck、Heike Heckroth
DOI:10.1055/s-2002-19335
日期:——
from enantiomerically pure (1b-l) α-amino acid methyl esters in high yields and irradiated in acetonitrile solutions with λ = 300 nm to give the β-lactams 2a-m as photocyclization products in moderate (38 and 40% for 2j and 2k) to excellent yields (85-100%) as racemic mixtures. The photocyclization is completely reversible in the absence of trace amounts of acid and the diastereoselectivity of the lactam