Convenient Synthesis of -Heterocycle-Fused Tetrahydro-1,4-diazepinones.

A general approach towards the synthesis of tetrahydro-4-pyrazolo[1,5-][1,4]diazepin-4-one, tetrahydro[1,4]diazepino[1,2-]indol-1-one and tetrahydro-1-benzo[4,5]imidazo[1,2-][1,4]diazepin-1-one derivatives was introduced. A regioselective strategy was developed for synthesizing ethyl 1-(oxiran-2-ylmethyl)-1-pyrazole-5-carboxylates from easily accessible 3(5)-aryl- or methyl-1-pyrazole-5(3)-carboxylates. Obtained intermediates were further treated with amines resulting in oxirane ring-opening and direct cyclisation-yielding target pyrazolo[1,5-][1,4]diazepin-4-ones.