Reaction of 2,3-dimethyl-1,3-butadiene with chiral (E)-2-cyanocinnamates
- Avenoza, A. 1
- Cativiela, C.
- Mayoral, J.A. 2
- Peregrina, J.M. 1
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1
Universidad de La Rioja
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2
Instituto de Nanociencia y Materiales de Aragón
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ISSN: 0957-4166
Year of publication: 1992
Volume: 3
Issue: 7
Pages: 913-919
Type: Article
beta Ver similares en nube de resultadosMore publications in: Tetrahedron: Asymmetry
Abstract
The reactions of 2,3-dimethyl-1,3-butadiene with (E)-2-cyanocinnamates of (S)-ethyl lactate (1a) and (R)-pantolactone (1b), catalysed by TiCl4, afford enantiomerically pure cycloadducts which are easily converted into the enantiomers (1R, 6S) and (1S, 6R) of the methyl 1-cyano-3,4-dimethyl-6-phenyl-3-cyclohexen-1-carboxylate. The reactions with TiCl4 can be explained by the dienophile-TiCl4 chelate model proposed by Helmchen. The non-catalysed reaction of (1b) with the same diene takes place at 100°C, with a moderately high d.e. and reversal of selectivity.