Synthesis of substituted 1H- and 3H-1-benzazepines: Rearrangement of 2-alkoxycarbonyl-1H-1-benzazepines to isoquinolines

The SnCl2-mediated reduction of nitro groups in 2-nitro-4-(2-nitro-benzylidene)-alkanoates and 4-nitro-2-(2-nitro-alkylidene)-alkanoates afforded via SN2′ reaction of ethyl nitroacetate and nitroethane with the acetyl derivatives of Baylis-Hillman adducts afforded by 2-nitro-substituted benzaldehydes leads to facile synthesis of substituted 1H-1-benzazepine and 3H-1-benzazepine. During the study an unprecedented rearrangement of 2-alkoxycarbonyl-1H-benzazepine to substituted isoquinoline has been observed.

A Facile synthesis of 3-Methylene-4-aryl-1,3,4,5-tetrahydro-benzo[b][1,4] di-azepin-2-ones and 3-arylemethylene-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-ylamines

A simple and convenient synthesis of 3-methylene-4-aryl-1,3,4,5-tetrahydro-benzo[b][1,4] diazepin-2-ones was accomplished by the SN2 nucleophilic substitution of the acetates of Baylis-Hillman adducts of acrylate with 1,2-phenylenediamines followed by base-mediated intramolecular cyclization. On the other hand similar substrates derived from the Baylis-Hillman adducts of acrylonitrile via Pinner’s reaction leads to 3-arylmethylene-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-ylamines in good yields..

Application of primary allyl amines afforded by the Baylis-Hillman adducts for heterocyclic synthesis: Generation of 5-benzyl-4(3H)-pyrimidinones and 2-benzylidene-2,3-dihydro-pyrrolizin-1-ones

The applications of the primary allyl amines afforded by the acetyl derivative of Baylis-Hillman adducts of acrylate for the synthesis of heterocycles using robust reactions are described. In the first strategy a one-pot synthesis of 5-benzyl-4(3H)-pyrimidinones have been achieved via N-formylation of the amines in the presence of neat formamide followed by ammonium formate-mediated cyclization. These pyrimidinones have been demonstrated to be excellent precursor to the 4-pyridinamine derivatives. In the second strategy the synthesis of 2-benzylidene-2,3-dihydro-pyrrolizin-1-ones have been accomplished via treatment of allyl amine with dimethoxyfuran followed by saponification and PPA-mediated intramolecular cyclization.