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Conjugate Addition versus Cycloaddition/Condensation of Nitro Compounds in Water: Selectivity, Acid–Base Catalysis, and Induction Period
Author(s) -
Guideri Luca,
De Sarlo Francesco,
Machetti Fabrizio
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201202698
Subject(s) - conjugate , chemistry , selectivity , catalysis , induction period , base (topology) , nitro , chloroform , medicinal chemistry , ammonium , tautomer , condensation , conjugate acid , organic chemistry , ion , mathematical analysis , alkyl , physics , mathematics , thermodynamics
Nitroacetates and nitroacetamides react in water as in chloroform with electron‐deficient dipolarophiles to give condensation or conjugate addition products under base catalysis. In general, high selectivity towards condensation is observed in water, with shorter induction periods than in chloroform. In water, condensations slowly occur even without base; kinetic profiles evidence the catalytic effect of the base, which should be related to the conversion into the tautomer nitronic acid. Condensations in water provide convenient access to isoxazole derivatives bearing various functional groups including ammonium, carboxy, and carboxyamide.