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Organophosphorus chemistry, 36[1]reactions of furobenzopyran-6-carboxaldehydes with alkyl phosphites and ylidenetriphenylphosphoranes [Witting reagents]
Egyptian Journal of Chemistry. 2007; (Special Issue): 45-58
em Inglês | IMEMR | ID: emr-82189
ABSTRACT
Dialkyl phosphites [4] and trialkyl phosphites [5] attack the aldehydic carbonyl carbon of 4-methoxy-5-oxo-5H-furo[3,2-g] benzopyran-6-carboxaldehyde [3a] and 4,9-dimethoxy-5-oxo-5H-furo [3,2-g] benzopyran-6- carboxaldehyde [3b] yielding the corresponding alpha-hydroxyphosphonates [7]. Compounds 7 regenerate the starting gamma-pyrone derivatives [3a or 3b] and the appropriate dialkyl phosphites [4] upon thermolysis under reduced pressure. On the other hand, the reaction of 3 with ylidenetriphenylphosphoranes [6] proceeds according to the Wittig mechanism to give the respective ethylenes [E 17]. The reaction of 3b with diethyl cyanomethylphosphonate [18] under Homer-Wittig conditions yields 6-[[alpha-cyano-alpha diethoxyphosphoryl] ethyliden-yl]-4,9-dimethoxy-5-oxo-5H-furo [3,2-g] benzopyran [20]. Structures of the isolated new products were elucidated by compatible, analytical, chemical and spectroscopic measurements
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Índice: IMEMR (Mediterrâneo Oriental) Assunto principal: Compostos Organofosforados / Fosfitos / Indicadores e Reagentes Idioma: Inglês Revista: Egypt. J. Chem. Ano de publicação: 2007

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Índice: IMEMR (Mediterrâneo Oriental) Assunto principal: Compostos Organofosforados / Fosfitos / Indicadores e Reagentes Idioma: Inglês Revista: Egypt. J. Chem. Ano de publicação: 2007