In this report, we describe a new method for the synthesis of densely functionalized 2(1H)-pyrazinones. Treatment of mesoionic 1,3-oxazolium-5-olates with carbanions derived from activated methylene isocyanides (p-toluenesulfonylmethyl isocyanide (TosMIC) and ethyl isocyanoacetate) causes a novel ring transformation affording 2(1H)-pyrazinones in moderate to high yields. The cytotoxicity and antibacterial
Synthesis of Trifluoromethyl-Substituted Pyrazoles and 1,2,4-Triazines by Ring Transformation of Mesoionic 4-Trifluoroacetyl-1,3-oxazolium-5-olates with Phenylhydrazine
作者:Masami Kawase、Hiromi Koiwai
DOI:10.1248/cpb.56.433
日期:——
Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates 1 were easily prepared by the cyclodehydration reaction of N-acyl-N-alkyl-alpha-amino acids with trifluoroacetic anhydride. Due to the presence of the trifluoromethyl ketone and the mesoionic five-membered oxazole, there are three reaction sites to be attacked by the nucleophiles at C-2, C-5 and the trifluoroacetyl group in 1. Based on this model,
Facile Synthesis of Imidazo[1,5-a]pyrazin-8(7H)-ones from Mesoionic 1,3-Oxazolium-5-olates via a Multistep One-Pot Transformation
作者:Masami Kawase、Ryosuke Saijo、Hidemitsu Uno
DOI:10.3987/com-16-13551
日期:——
A novel one-pot conversion of mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates into imidazo[1,5-a]pyrazin-8(7.H)-ones by the reaction with TosMIC is described. The structure of the product was determined by single-crystal X-ray analysis.
Novel ring transformation of mesoionic oxazoles into 2(1H)-pyrazinones by the reaction with TosMIC
Treatment of mesoionic 1,3-oxazolium-5-olates with TosMIC in the presence of a base causes a novel ring transformation affording 2(1H)-pyrazinones in moderate yields. The origin of C-2 carbonyl oxygen in the product was elucidated to be molecular oxygen, based on O-18-labeling experiments.[GRAPHICS].(C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.