Synfacts 2011(3): 0252-0252  
DOI: 10.1055/s-0030-1259503
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Copper-Catalyzed Synthesis of Heterofused Benzoxazepines and -diazepines

Contributor(s): Victor Snieckus, Toni Rantanen
M. Nayak, S. Batra*
Central Drug Research Institute, Lucknow, India
Further Information

Publication History

Publication Date:
16 February 2011 (online)

Significance

A method for the synthesis of heteroannulated pyrazoles is presented. The protocol involves an intermolecular condensation between substituted pyrazole-4-iodo-3-carboxaldehydes and 1,2-diamino- or 1-amino-2-hydroxybenzenes followed by a copper-catalyzed C-N or C-O coupling to afford the heterofused benzazepines and benzoxazepines, respectively. For the C-N coupling, two sets of conditions, one using l-proline as ligand (A), and another, a ligand-free (B) process, were identified. In all cases studied, method B provided yields 5-20 percent units higher than method A. For the C-O coupling, 1,10-phenanthroline as ligand and Cs2CO3 as base were required. The yields generally range from mediocre to good; in one instance the reaction failed completely (R4 = 4-O2N). The substrate scope was reasonably well studied in terms of the pyrazole, less so with the other counterpart (possibly dictated by the commercial availability).