New Efficient Synthesis of 6,12-Dihydro-5H-quinazolino[3,2-a] quinazolin-5-ones via Ugi/Staudinger/Aza-Wittig/Addition/Nucleophilic Acyl Substitution Sequence

Abstract

AbstractA new efficient synthesis of 6,12-dihydro-5H-quinazolino[3,2-a]quinazolin-5-ones by sequential Ugi/Staudinger/aza-Wittig/addition/nucleophilic acyl substitution has been developed. α-Amino amides, obtained from Ugi-3CR of 2-azidobenzaldehydes, methyl 2-aminobenzoates, and isocyanides in the presence of catalytic amount of phenylphosphinic acid, reacted with triphenylphosphine and isocyanates to give 6,12-dihydro-5H-quinazolino[3,2-a]quinazolin-5-ones in good yields. This method provides a domino and effective strategy for the preparation of various substituted quinazolino[3,2-a]quinazolin-5-ones under mild reaction condition.