Synthesis of a series of novel fused tetracyclic mono- and diazaindolo[2,1-c][1,4]benzoxazine heterocyclic compounds 3a–o has been achieved in a two-step one-pot reaction set up starting from commercially available or easily accessible inputs. For example, reaction of di-lithiated (N-Boc)-2-amino-3-methylpyridine Li2–2a with Weinreb amide of 2-(2,4-difluorophenoxy)-2,2-dimethylacetic acid 1a, followed by TFA treatment furnished the tetracyclic compound 3a, which is essentially a fusion of 7-azaindole and 3,4-dihydro[1,4]benzoxazine, in 70% isolated yield. A competitive elimination by-product 4a was also observed (24% isolated yield) in this case. Based on our initial results, a structural basis and molecular mechanism have been suggested to explain these two parallel reactions. Consequently, with appropriate structural tuning of 1, formation of the individual products can be controlled.

Synthesis of a novel tetracyclic azaindolo[2,1-c][1,4]benzoxazine ring system / S. Kurhade, R.D. Kaduskar, B. Dave, P.A. Ramaiah, V. P. Palle, D. Bhuniya. - In: TETRAHEDRON LETTERS. - ISSN 0040-4039. - 52:16(2011 Apr 20), pp. 1874-1877.

Synthesis of a novel tetracyclic azaindolo[2,1-c][1,4]benzoxazine ring system

R.D. Kaduskar;
2011

Abstract

Synthesis of a series of novel fused tetracyclic mono- and diazaindolo[2,1-c][1,4]benzoxazine heterocyclic compounds 3a–o has been achieved in a two-step one-pot reaction set up starting from commercially available or easily accessible inputs. For example, reaction of di-lithiated (N-Boc)-2-amino-3-methylpyridine Li2–2a with Weinreb amide of 2-(2,4-difluorophenoxy)-2,2-dimethylacetic acid 1a, followed by TFA treatment furnished the tetracyclic compound 3a, which is essentially a fusion of 7-azaindole and 3,4-dihydro[1,4]benzoxazine, in 70% isolated yield. A competitive elimination by-product 4a was also observed (24% isolated yield) in this case. Based on our initial results, a structural basis and molecular mechanism have been suggested to explain these two parallel reactions. Consequently, with appropriate structural tuning of 1, formation of the individual products can be controlled.
(N-Boc)-2-amino-3-methylpyridine; 2-(2,4-Difluorophenoxy)-2,2-dimethylacetic acid; Azaindolo[2,1-c][1,4]benzoxazine; Diazaindolo[2,1-c][1,4]benzoxazine; Weinreb amide
Settore CHIM/06 - Chimica Organica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/255822
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