Synthesis of 3-Alkylcoumarins and 3-Alkyl

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from 3-Diethylphosphonocoumarins, 3-Diethylphosphonolactones ... The treatment of salicylaldehyde 1 and derivatives 2-4 with triethyl phosphonoacetate 5.
Synthesis of 3-Alkylcoumarins and 3-Alkyl-«,/?-unsaturated ^-Lactones from 3-Diethylphosphonocoumarins, 3-Diethylphosphonolactones and Aldehydes G. Falsone*, F. Cateni, M. M. De Nardo, M. M. Darai Department of Pharmaceutical Sciences, University of Trieste, P.zle Europa 1,1-34127 Trieste Z. Naturforsch. 48 b, 1391-1397 (1993); received June 25,1993 3-Phosphonocoumarins, 3,4-Dihydrophosphonocoumarins, 3-Alkylcoumarins The treatment of salicylaldehyde 1 and derivatives 2 -4 with triethyl phosphonoacetate 5 in refluxing toluene using piperidine acetate and /?-alanine affords 3-diethyl phosphonocoumarins 6 -9 . By hydrogenation of the compounds 6-9, 3-diethylphosphono-3,4-dihydrocoumarins 10-13 have been obtained. The compounds 10-13 react with the aromatic alde­ hydes 14-18, under Wittig-Horner conditions, to give 3-alkyl-coumarins 19-24 in satisfac­ tory yields. The reaction of 3-diethyl-phosphonolactones 25, 26 with isatin 27 and 5-bromoisatin 28, under similar reaction conditions, leads to 3-alkyl-a,/?-unsaturated