A New synthesis of highly fufictionalized 5-azaqumarines

1. A New synthesis of highly fufictionalized 5-azaqumarines Bita Mohtat a,Issa Ya\-ari,a,bHasan Zare b . Department of Chemistry, Islamic Azad [; niversity, Karadj, Iran aand Department of Chemistry, Tarbiat Modarres University, Tehran, Iran a,b Summary 3-hydroxy pyridine undergoes a smooth reaction with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine to produce phosphorus ylide intermediates, which produce alkyl 2-oxo-2H-pyrano[3,2-b ]pyridine-4-carboxylate 3a-3d, and alkyl 6-«E)-1 ,2-di(alkoxycarbon~-I)vinyl)-2-oxo-2H-pyrano[3,2-b ]pyridine-4- carboxylate 4a-4d. Under the same reaction conditions, di-tert-butyl or di-iso-propyl acetylenedicarboxylate produces dialkyl 2-(5-hydroxypyridin-2-yl)but-2-enedioate Sa- Sb. Key-vords: 3-hydroxypyridine; triphenylphosphine; acetylenic ester; phosphorus ylide. Corresponding authors. Fax: +98(21)800654-1r; E-mail: yavarisa@modares.ac.ir Introduction The addition reaction between electron-deficient acetylenic compounds and nitrogen- containing hetrocycles has been extensivel~' investigated [1-4]. We report herein that dialkyl acetylenedicarboxylate undergoes addition reaction with 3-hydroxy pyridine in the presence of triphenylphosphine, yielding alkyl 2-oxo-2H-pyrano[3,2-b ]pyridine-4- carboxylate 3a-3d, and alkyl 6-«E)-1,2-di(alkoxycarbonyl)vinyl)-2-oxo-2H-pyrano[3,2- b]pyridine-4-carboxylate 4a-4d. Under the same reaction conditions, di-tert-butyl or di-