Synthesis 2011(20): 3379-3388  
DOI: 10.1055/s-0030-1260189
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Direct Transformation of Baylis-Hillman Acetates into N-Substituted Quinolones through an SN2′ → SNAr → (Δ3,42,3 Shift) → Oxidation Sequence

John Victor Napoleon, Muraleedharan Kannoth Manheri*
Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
Fax: +91(44)22574202; e-Mail: mkm@iitm.ac.in;
Further Information

Publication History

Received 18 May 2011
Publication Date:
05 September 2011 (online)

Abstract

When subjected to tandem SN2′-SNAr cyclization in the presence of alkyl or aralkyl amines, Baylis-Hillman acetates gave the corresponding 1,2-dihydroquinolines, which on simple exposure to light and oxygen afforded the corresponding 4- and 2-quinolones through sensitized oxidation or a Δ³,4²,³ shift → oxidation cascade. The mechanism of the oxidation step, the stabilities of the 1,2- and 1,4-dihydroquinolines in solution and in the solid state, and the synthetic elaboration of the key intermediates to known therapeutic agents are discussed.

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Crystallographic data for compounds 4a (R4 = Bn), 6.7, and 7.7 have been deposited with the Cambridge Crystallographic Data Centre as supplementary publications CCDC 779998, CCDC 771058, and CCDC 771059, respectively; copies can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44 (1223)336033 or email: deposit@ccdc.cam.ac.uk].