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Synthesis 2001(6): 0849-0854
DOI: 10.1055/s-2001-13403
PAPER
© Georg Thieme Verlag Stuttgart · New York

Efficient Synthesis and Spectroscopic Analysis of 8-Nitro Spiro C-3-Annulated 2-Benzazepines and their N-Oxides

Alexey Varlamov*a, Vladimir Kouznetsovb, Fedor Zubkova, Alexey Chernysheva, Grigorii Alexandrova, Alirio Palmab, Leonor Vargasb, Sandra Salasb
a Department of Organic Chemistry, Russian Peoples Friendship University, Moscow, 117923, Russia
b Laboratory of Fine Organic Synthesis, School of Chemistry, Industrial University of Santander, A.A. 678, Bucaramanga, Colombia
Further Information

Publication History

Received 3 December 2000
Publication Date:
24 September 2004 (online)

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Abstract

Nitroderivatives 9a-g have been prepared with great C-8 regioselectivity by allowing the corresponding 1,2,4,5-tetrahydrospiro[3H-2-benzazepine-3,1"-cycloalkanes] 8a-g to react with potassium nitrate and concentrated H2SO4. The oxidative reaction of a nitrogen-carbon bond in spirobenzazepines 8 and 9 was performed with H2O2 and catalytic amounts of sodium tungstate at room temperature affording nitrones 10a-d in moderate to high yields. Stereochemical assignments for all the 2-benzazepine derivatives obtained were derived from a full analysis of the 1H NMR spectroscopic data and an X-ray crystallographic analysis of 1,5-dimethyl-8-nitro-1,2,4,5-tetrahydrospiro[3H-2-benzazepine-3,1"-cyclohexane] 9c. These data indicate that the 2-benzazepines 8-11 in solution present the azepine ring preferably in the chair conformation, with the methyl substituent at C-5 disposed equatorially.

Key words

2-benzazepines - regioselective nitration - homoallyl-amines - nitrones

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Atomic coordinates for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre. The coordinates can be obtained, on request, from the Director, Cambridge Crystallographic Centre, 12 Union Road, Cambridge CB2 1EZ, UK.