Synthesis and reactions of 3-hydroxy-2-nosyloxy esters produced by the stereoselective reduction of 2-nosyloxy-3-keto esters
摘要:
The reduction of 2-nosyloxy-3-keto esters is an effective method for the preparation of 3-hydroxy-2-nosyloxy esters. The reduction is stereoselective for the syn isomer. The anti isomer can be produced as the major product by the addition of p-nitrobenzenesulfonyl peroxide to ketene bis-silyl acetal derivatives of 3-hydroxy esters. The diastereomers are separable chromatographically and can be converted stereospecifically to glycidic esters and 2-azido-3-hydroxy esters. As such they appear to have excellent potential as versatile synthetic intermediates for the synthesis of 1,2,3-trifunctional substances.
Synthetic transformations using arenesulfonyloxy groups, first as electrophiles, then as leaving groups
作者:Robert V. Hoffman
DOI:10.1016/s0040-4020(01)86369-9
日期:1991.1
Lee, Jong Chan; Choi, Ju-Hee, Synlett, 2001, # 2, p. 234 - 235
作者:Lee, Jong Chan、Choi, Ju-Hee
DOI:——
日期:——
Synthesis of 2-Oxazolone-4-carboxylates from 3-Nosyloxy- and 3-Bromo-2-ketoesters
作者:John F. Okonya、Robert V. Hoffman、M. Catherine Johnson
DOI:10.1021/jo010630z
日期:2002.2.1
New methods for the synthesis of 2-oxazolone-4-carboxylates from 3-nosyloxy- and 3-bromo-2-ketoesters are described. Condensation of 3-nosyloxy-2-ketoesters with methyl carbamate in refluxing toluene in the presence of p-TSA provided 2-oxazolone-4-carboxylates in good yields (41-80%). Alternatively, bromination of alpha-ketoesters with CuBr2 provided 3-bromo-2-ketoesters which condensed with methyl carbamate in the presence of p-TSA and AgOTf under similar conditions to provide 2-oxazolone-4-carboxylates in comparable yields (30-79%). The 2-oxazolone-4-carboxylates bear functionality that can be elaborated to a variety of potentially useful compounds. For example, some of these heterocycles were readily N-acylated, reduced to alcohols, or saponified and coupled with amino acids.
2-[[(p-Nitrophenyl)sulfonyl]oxy]-3-keto esters: versatile intermediates for the preparation of 1,2,3-tricarbonyl compounds
作者:Robert V. Hoffman、Hwa Ok Kim、Anna Lee Wilson
DOI:10.1021/jo00296a047
日期:1990.4
HOFFMAN, ROBERT V.;WILSON, ANNA LEE;KIM, HWA-OK, J. ORG. CHEM., 55,(1990) N, C. 1267-1270
作者:HOFFMAN, ROBERT V.、WILSON, ANNA LEE、KIM, HWA-OK