The o.formylarylazomethylenetriphenylphosphoranes carrying an electron withdrawing group on the ylidic carbon undergo thermal intra molecular cyclization to 3-oxo-indazolin-2-yl-methylenetriphenylphosphorane derivatives. The latter compounds, and their 1-alkyl derivatives, in turn, undergo thermal and/or acid catalyzed rearrangement to 4-oxo-l,4-dihydroquinazoline derivatives and PPh3. Some possible reaction mechanisms are discussed, and some synthetic applications of the above reactions are shown. © 1985.
Alemagna, A., Delbuttero, P., Licandro, E., Maiorana, S., Papagni, A. (1985). ORTHO-FORMYLARYLAZOMETHYLENETRIPHENYLPHOSPHORANES - A FACILE THERMALLY PROMOTED REARRANGEMENT TO 3-OXO-INDAZOLINE AND 4-OXO-DIHYDROQUINAZOLINE DERIVATIVES. TETRAHEDRON, 41(16), 3321-3330 [10.1016/S0040-4020(01)96683-9].
ORTHO-FORMYLARYLAZOMETHYLENETRIPHENYLPHOSPHORANES - A FACILE THERMALLY PROMOTED REARRANGEMENT TO 3-OXO-INDAZOLINE AND 4-OXO-DIHYDROQUINAZOLINE DERIVATIVES
PAPAGNI, ANTONIO
1985
Abstract
The o.formylarylazomethylenetriphenylphosphoranes carrying an electron withdrawing group on the ylidic carbon undergo thermal intra molecular cyclization to 3-oxo-indazolin-2-yl-methylenetriphenylphosphorane derivatives. The latter compounds, and their 1-alkyl derivatives, in turn, undergo thermal and/or acid catalyzed rearrangement to 4-oxo-l,4-dihydroquinazoline derivatives and PPh3. Some possible reaction mechanisms are discussed, and some synthetic applications of the above reactions are shown. © 1985.
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