In Situ Carboxyl Activation Using a Silatropic Switch: A New Approach to Amide and Peptide Constructions
摘要:
The novel reactivity of O-silylthionoesters with amine nucleophiles to generate oxoamides (rather than thioamides) is described. A straightforward first-generation trimethylsilylation protocol using bistrimethylsilylacetamide (BSA) combined with the unique reactivity of the O-silylthionoesters toward 1 degrees and 2 degrees amines to generate oxoamides provides the simplest means of activating a thiol acid for peptide bond formation at neutral pH. Excellent stereoretention is observed.
[EN] AN IMPROVED PROCESS FOR PREPARATION OF AMISULPRIDE<br/>[FR] PROCÉDÉ AMÉLIORÉ DE PRÉPARATION D'AMISULPRIDE
申请人:LUPIN LTD
公开号:WO2011158084A1
公开(公告)日:2011-12-22
The present invention is related to a novel process for the preparation of amisulpride (I) which involves : methylation of 4-amino-salicylic-acid (VI) with dimethyl sulphate and base, optionally in presence of TBAB to obtain 4-amino-2-methoxy methyl benzoate (VII) and (ii) oxidation of 4-amino-2-methoxy-5-ethyl thio benzoic acid (IX) or 4-amino-2-methoxy-5- ethyl thio methyl benzoate (X) with oxidizing agent in the presence of sodium tungstate or ammonium molybdate to give 2-methoxy-4-amino-5-ethyl-sulfonyl benzoic acid (IV) or 2- methoxy-4-amino-5-ethyl-sulfonyl methyl benzoate (XI) respectively.
Regio‐ and Stereoselective Chan‐Lam‐Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines
作者:Luuk Steemers、Linda Wijsman、Jan H. van Maarseveen
DOI:10.1002/adsc.201800914
日期:2018.11.5
Efficient and scalable Cu(II)‐mediated enol esterification methodology of carboxylicacids from alkenyl boroxines and boronic acids is presented. The reaction shows a wide scope in aliphatic and aromatic carboxylicacids in combination with several alkenyl boroxines. In the case of 2‐substituted alkenyl boroxines the double bond configuration was fully retained in the enol ester product. Also N‐hydroxyimides
Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 13.1 Extrusion of Ph3P from sulfinyl ylides and reactivity of the resulting sulfinyl carbenes
作者:R. Alan Aitken、Martin J. Drysdale、Bruce M. Ryan
DOI:10.1039/a806182c
日期:——
Six α-sulfinyl phosphorus ylides 6 have been prepared and are found upon flashvacuumpyrolysis at 500 °C to undergo mainly extrusion of Ph3P to give thioesters, presumably by 1,2-oxygen transfer in the initially formed sulfinyl carbenes; for α-arylsulfinyl ylides loss of Ph3PO to give additional products is also observed.
An interesting procedure for thioester synthesis via nickel-catalyzed thiocarbonylation of arylboronic acid with sulfonyl chlorides as the sulfur source has been explored. Using Mo(CO)6 as a solid CO surrogate and reductant, a broad range of thioesters were obtained in moderate to good yields with good functional group tolerance.