Reaction of alk-3-yn-1-ones with non-symmetricalo-phenylenediamines provides an effective method with high atom economy for the synthesis of diversely substituted 1,5-benzodiazepines and conjugated enaminones.

Reaction of alk-3-yn-1-ones with o-phenylenediamines provides an effective method with high atom economy for the synthesis of diversely substituted benzodiazepines and conjugated enaminones. This microwave-accelerated reaction proceeds in ethanol in the absence of a catalyst and leads to benzyl-substituted 1,5benzodiazepines with good yields (70-92%). A room temperature protocol with the same set of reagents (stabilized with triethylamine) leads to enaminones (3-amino-2-alkenones, 70-99%). The tautomer formed and the regio-and stereochemistry of the process are confirmed by the X-ray crystallographic structure determination of 2-(4-methylbenzyl)-4-phenyl-3H-benzo[b][1,5]diazepine and (Z)-3-[(2-amino-4,5-dimethylphenyl)amino]-4-(4-tert-butylphenyl)-1-(4-chlorophenyl)but-2-en-1-one. Scheme 1 The synthesis of 1,5-diazepines 3 from alk-3-ynones 1 and o-phenylenediamines 2. † Electronic supplementary information (ESI) available: 1 H and 13 C NMR spectra for diazepines 3, enaminones 4 and 6, and cif files for 3aa and 4cb. CCDC 929588 and 950049. For ESI and crystallographic data in CIF or other electronic format see

5-Exo-dig cyclocondensation of alk-3-yn-1-ones with hydrazines, in the presence of montmorillonite K-10, provides an effective method with a high atom economy for the synthesis of diversely 1,3,5-trisubstituted pyrazoles. The microwave-accelerated reaction proceeds in the absence of solvent and leads to 5-benzyl substituted pyrazoles with good yields (72-91%). The regiochemistry of the process was confirmed by the X-ray crystallographic structure determination of 1-(2-fluorophenyl)-5-(4-methylbenzyl)-3-phenyl-1H-pyrazole.

An effective, highly atom economical, and regioselective method for the synthesis of the title compounds is presented and requires no isolation of the hydrazone.