The regiospecific synthesis of N-substituted pyrazoles. I. 1- and 2-substituted indeno[1,2-c]pyrazol-4(1H)-ones

The reaction of the enaminoketones ( 2 or 5 ) of 2-acyl-1,3-indandiones with unsymmetrical hydrazines results in the regiospecific synthesis of 1,3- or 2,3-disubstituted indeno1,2-c]pyrazol-4(1H)-ones ( 4 or 7 ). The synthesis of the enaminoketones ( 2 or 5 ) is accomplished by way of amine addition to the 2-acyl-1,3-indandiones 8a-c or by reduction of the indenoisoxazole 9 . The structural assignment of the isomeric indenopyrazoles 4 and 7 is based upon ¹H-nmr chemical shifts.