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A (1,3) Strain in cis- and trans-5, 6-dihydro-4, 6-dimethyl-4H, 8H-pyrido [3,2,1-de]phenanthridin-8-ones

Nagarajan, Kuppuswamy and Shah, Rashmi K and Fuhrer, Hermann and Puckett, Reginal T and Narasimhamurthy, Mathur R and Venkatesan, Kailasam (1978) A (1,3) Strain in cis- and trans-5, 6-dihydro-4, 6-dimethyl-4H, 8H-pyrido [3,2,1-de]phenanthridin-8-ones. In: Helvetica Chimica Acta, 61 (4). pp. 1246-1256.

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Abstract

The stereochemistry of trans- and cis-2, 4-dimethyl-tetrahydroquinolines, 6 and 7 were derived from 1H-NMR. studies. These were converted respectively into trans- and cis-5, 6-dihydro-4, 6-dimethyl-4H, 8H-pyrido [3, 2, 1-de]phenanthridin-8-ones 18 and 20 by a Pschorr reaction on the anthranilamides 10 and 15. Bromophenanthridones 19 and 21 were similarly prepared from bromoanthranilamides 12 and 17. Detailed 1H-NMR. studies on 18 and 20 indicated axial disposition of the methyl groups at C(2) in both compounds in contrast to the situation in 6 and 7. This is presumably to avoid adverse CH3CO group interaction of the A (1, 3) type. The severity of this is gauged by the preference of 20 for a normally forbidding 1, 3-diaxial orientation of two methyl groups. X-ray crystallographic studies on 19 and 20 confirm the stereochemical assignments.

Item Type: Journal Article
Additional Information: The copyright belongs to Verlag GmbH & Co. KGaA, Weinheim.
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Date Deposited: 26 Oct 2005
Last Modified: 27 Aug 2008 11:31
URI: http://eprints.iisc.ernet.in/id/eprint/3902

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