Karl G. Grozinger

Cross-coupling of 1-aryl-5-bromopyrazoles: regioselective synthesis of 3,5-disubstituted 1-arylpyrazoles

Abstract The cross-coupling of 1-aryl-5-bromopyrazoles 4 with alkynes, vinyltins and arylboronic acids promoted by Pd(PPh3)4 afforded unsymmetrical 3,5-disubstituted 1-arylpyrazoles 5-8 in excellent yields. 1-Aryl-5-bromopyrazoles 4 were prepared from their corresponding 1-arylpyrazolones 3 with PBr3 in refluxing acetonitrile.

A significantly improved condition for cyclization of phenethylcarbamates to N-alkylated 3,4-dihydroisoquinolones

Abstract Secondary phenethylcarbamates undergo a Bischler-Napieralski cyclization promoted by phosphorus pentoxide in refluxing phosphorus oxychloride to afford N-alkylated 3,4-dihydroisoquinolones in high yields.

Practical synthesis of 1,3-diaryl-5-alkylpyrazoles by a highly regioselective N-arylation of 3,5-disubstituted pyrazoles with 4-fluoronitrobenzene

Abstract 3-Aryl-5-alkylpyrazoles undergo a highly regioselective arylation on N-1 atom with 4-fluoronitrobenzene in the presence of base to yield the corresponding 1-(4-nitrophenyl)pyrazoles.