Preparation of Substituted Oxazoles by Ritter Reactions of α-Oxo Tosylates
作者:Mark Taylor、Ping-Shan Lai
DOI:10.1055/s-0029-1218682
日期:2010.5
The Lewis acid catalyzed Ritter reaction of α-oxo tosylates with nitriles forms the basis of an efficient synthesis of oxazoles. Oxazoles with various substituents can be readily prepared from inexpensive starting materials. heterocycles - cyclizations - nitriles - carbocations - oxazoles - Ritter reaction
The insertion reaction of diazocarbonyls to acids could be performed smoothly in fluorinated alcohols in the absence of metal catalyst. This new procedure allowed the chemoselective preparation of various functionalized compounds such as acyloxyesters, depsipeptides, and sulfonate, phosphonate, or boronate derivatives.
triflate and (R,R)-Ph-BOX as a catalyst. This method was successfully applied to a variety of 2-hydroxyalkanamides in high enantioselectivity with up to 92% ee, and then tosylated product was easily transformed into opticallyactive α-amino acid derivatives.
The synthesis of new (4S,8aS)- and (4R,8aS)-4-phenyl-perhydropyrrole[1,2-a]pyrazine-1,3-diones in the cyclocondensation reaction of the respective derivatives of L-prolineamide is described. The effect of the amount of NaOEt, temperature, and reaction time on the proportions of diastereomers formed in the cyclocondensation reaction was examined. The structures of the diastercomers were confirmed by GC/MS, FIRMS, HPLC; XRD, and H-1 and C-13 NMR investigations. (C) 2007 Elsevier Ltd. All rights reserved.
Reaction of [hydroxy(tosyloxy)iodo]benzene and [hydroxy(mesyloxy)iodo]benzene with trimethylsilyl enol ethers. A new general method for .alpha.-sulfonyloxylation of carbonyl compounds
作者:Robert M. Moriarty、Raju Penmasta、Alok K. Awasthi、W. Ruwan Epa、Indra Prakash