Synthesis of some thiochromeno 4,3-c - and 3,4-c -pyrazoles
Gabbutt, C. D., Hepworth, J. D., Heron, B. M., Coles, S. J. and Hursthouse, M. B. (2000) Synthesis of some thiochromeno 4,3-c - and 3,4-c -pyrazoles. Journal of the Chemical Society, Perkin Transactions 1, (17), 2930-2938. (doi: 10.1039/b004149l)
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Description/Abstract
Reaction of 3-hydroxymethylene- and 3-cyanomethylene-thiochroman-4-ones with various hydrazine derivatives affords 4H-thiochromeno[4,3-c]pyrazoles. The novel isomeric thiochromeno[3,4-c]pyrazoles result when 4-(dimethylaminomethylene)thiochroman-3-ones react with methyl- and phenyl-hydrazines. Acidic hydrolysis of 3-(dimethylhydrazonoethylidene)-2,2,6-trimethylthiochroman-4-one yields the 3-cyanomethylenethiochroman-4-one. Formation of 6-chloro-3-hydroxymethylenethiochroman-4-one is accompanied by a thiochroman-3-yl(oxothiochromen-3-yl)methane derivative produced through a rearrangement-carbocation interception sequence. A 3-isopropenylthiochromenone, obtained by the acid promoted rearrangement of a 3-hydroxymethylenethiochroman-4-one, undergoes Diels-Alder cycloadditions to provide a new route to thioxanthenones.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | cyclic beta-enaminones, substituted pyrazoles, fused heterocycles, stereochemistry, ketones, reactivity |
| Related URLs: | http://www.rsc.org/Publishing/...i=b004149l |
| Subjects: | Q Science Q Science > QD Chemistry |
| Divisions: | University Structure - Pre August 2011 > School of Chemistry |
| ePrint ID: | 18868 |
| URI: | http://eprints.soton.ac.uk/id/eprint/18868 |
| Deposited On: | 21 Dec 2005 |
| Last Modified: | 01 Jun 2011 02:45 |
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