58329-12-7Relevant articles and documents
Hexacarbonylmolybdenum-induced Reaction of Isoxazoles. Cycloaddition of Isoxazoles with Acetylenic Esters and Related Reactions
Kobayashi, Tomoshige,Nitta, Makoto
, p. 152 - 157 (2007/10/02)
In the presence of hexacarbonylmolybdenum, substituted isoxazoles undergo a cycloaddition reaction with dimethyl acetylenedicarboxylate across the C-4-C-5 bond to give 3,4-bis(methoxycarbonyl)pyridine derivatives.In a similar cycloadition of isoxazoles with methyl propiolate, 4-(methoxycarbonyl)pyridine derivatives were also obtained.The β-carbon atom of methyl propiolate could intervene in the bonding with the C-5 position of the isoxazoles regioselectively.A mechanism involving a complexed 2-oxa-3-azabicyclohepta-3,6-diene derivative and the subsequent N-Oand C-1-C-5 bond cleavage leading to a complexed (β-ketovinyl)nitrene intermediate is proposed for the formation of pyridine derivatives.In order to clarify the mechanistic aspect, the reaction of 4-phenyl-2-oxa-3-azabicyclohepta-3,6-diene and its related compounds were also studied to give pyridine derivatives.
Cycloaddition Reaction of Dimethyl Acetylenedicarboxylate with 2,4,5-Triphenyl-3H-pyrrol-3-one 1-Oxide
Freeman, Jeremiah P.,Haddadin, Makhluf J.
, p. 4898 - 4902 (2007/10/02)
The reaction of 2,4,5-triphenyl-3H-pyrrol-3-one 1-oxide with dimethyl acetylenedicarboxylate gave pyridine 9a, 4(3H)-pyridone 10a, isoxazolidine 11, and traces of pyridone 13.Pyridone 10a is not an intermediate in the formation of 9a, yet on photolysis or pyrolysis above its melting point, 10a yielded pyridine 9a.Possible reaction mechanisms that rationalize the formation of these products are discussed.