Improved Synthesis of Methyl Alkoxyacetylenecarboxylates
作者:Francisco Camps、Josep Coll、Amadeu Llebaria、Josep M. Moretó、Susagna Ricart
DOI:10.1055/s-1989-27168
日期:——
The title compounds 3a-d can be satisfactorily prepared by the reaction of lithium alkoxyacetylides with methyl chloroformate in tetrahydrofuran at - 78°C, in the presence of a 3.5 molar excess of lithium bromide (based on chloroformate). Moderate to good yields of 3a-d were obtained according to the product stabilities. However, methyl tert-butoxyacetylenecarboxylate (3e) was too unstable to be isolated. The putative dual role of the lithium salt and the formation of substantial amounts of carbonates, observed in its absence, are discussed.
Formation of a PIII−C(sp2) bond by addition of diphenyl(trimethylsilyl)phosphine to activated acetylenes
作者:A. N. Kochetkov、I. V. Efimova、I. G. Trostyanskaya、M. A. Kazankova、I. P. Beletskaya
DOI:10.1007/bf02495698
日期:1998.9
Diphenyl(trimethylsilyl)phosphine reacts with alkoxy(alkyl)acetylenes to give mixtures of addition products, (2-alkoxy-2-trimethylsilylalkenyl)diphenylphosphines and (2-alkoxyalkenyl)diphenylphosphines. The reaction is sensitive to the solvent; in MeCN, it gives only nonsilylated products. (1-Alkoxyethenyl)diphenylphosphines were obtained as the main products upon the reaction of Ph2PSiMe3 with terminal
Synthesis of <i>tert</i>-Alkyl Amino Hydroxy Carboxylic Esters via an Intermolecular Ene-Type Reaction of Oxazolones and Enol Ethers
作者:Robert A. Mosey、Jason S. Fisk、Timothy L. Friebe、Jetze J. Tepe
DOI:10.1021/ol702941f
日期:2008.3.1
tert-Alkyl amino hydroxy carboxylic acids are abundantly present within the structure of many biologically active natural products. We describe herein the synthesis of these substrates using an oxazolone-mediated ene-type reaction with enolethers followed by NaBH4 reduction of the intermediate oxazolone.