Synthesis 2001(12): 1784-1789
DOI: 10.1055/s-2001-17509
PAPER
© Georg Thieme Verlag Stuttgart · New York

Observations on the DDQ Oxidation of 1-Acyldihydropyridines - A Synthetic Application

Debra J. Wallace*, Andrew D. Gibb*, Ian F. Cottrell, Derek J. Kennedy, Karel M. J. Brands, Ulf H. Dolling
Department of Process Research, Merck Sharp & Dohme Research Laboratories, Hertford Road, Hoddesdon, Hertfordshire, EN11 9BU, UK
Fax: +44(1992)452581; e-Mail: debra_wallace@merck.com;
Further Information

Publication History

Received 8 May 2001
Publication Date:
11 August 2004 (online)

Abstract

A synthetic application of the rate difference in oxidation of regioisomerically substituted N-acyldihydropyridines is reported. This has allowed for isolation of pure 4-substituted pyridine isomers without the need for chromatography. Diels-Alder adducts between a dihydropyridine and DDQ were isolated and formation of novel hydroquinone ethers was also observed during some reactions.

4

To the best of our knowledge the effect of the counterion has not been studied in detail.

6

Based on selectivity for the addition reaction.

7

The two isomers could not be unambiguously assigned.

10

The high temperature and long reaction time may lead to some decomposition, lowering the final yield compared to the oxidations of the 4-substituted compounds.