Reaction of 1-arylmethylidenepyrazolidin-1-azomethine imines with aryl ketenes

Abstract

A reaction of aryl ketenes with 1 arylmethylidenepyrazolidin 1 azomethine imines, gen erated by the diaziridine ring opening in 6 aryl 1,5 diazabicyclo[3.1.0]hexanes catalyzed with Et 2 O•BF 3 , leads to 1,2 bis(phenylacetyl)pyrazolidine, 2 arylacetyl 1 arylidenepyrazolidin 1 ium chlorides, or a representative of 1,5 diazabicyclo[3.3.0]octan 2 ones, viz., 4 (4 eth oxyphenyl) 3,3 diphenyl 1,5 diazabicyclo[3.3.0]octan 2 one, depending on the reaction con ditions and the structure of the starting compounds. A mechanism suggested earlier for the transformation of 1,5 diazabicyclo[3.1.0]hexanes in the reaction with ketenes was confirmed.

Selective and reversible 1,3-dipolar cycloaddition of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with 1,3-diphenylprop-2-en-1-ones under microwave irradiation

“…However, the selectivity of the cycloaddition for thermal or catalytic conditions can be different [ 25 ]. It was possible to obtain the cycloaddition products of unstable azomethine imines with carbon disulfide [ 26 ], diphenylketene [ 27 ], β-nitrostyrenes [ 28 – 29 ], if ionic liquids (IL) were used as reaction media. The reaction of β-nitrostyrenes with azomethine imines proceeds giving mixtures of Michael and anti -Michael-type adducts, containing a nitro group at the C 2 - or C 1 -position of the hexahydropyrazolo[1,2- a ]pyrazole ring, respectively, apparently through zwitterionic intermediates [ 28 – 29 ].…”