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P. Müller, Y.F. Allenbach, S. Grass,
“Enantioselective Intramolecular Cyclopropanation of Allyl 2-diazo-3-silanyloxybut-3-enoates”
Tetrahedron: Asymmetry 2005, 16, 2007-2013.
The performance of the [Rh2{(S)-ntt}4]-catalyst in comparison to [Rh2{(S)-pttl}4] and [Rh2{(S)-dosp}4] has been examined with allyl 2-diazo-3-silanyloxybut-3-enoates. The best results were obtained with [Rh2{(S)-pttl}4], where enantioselectivity culminated at 89% ee at −78 °C. [Rh2{(S)-ntt}4] was slightly less selective, while [Rh2{(S)-dosp}4] was found less suitable for these substrates. However, even the results obtained with [Rh2{(S)-pttl}4] are much less satisfactory than those for the intramolecular cyclopropanation of allyl diazoacetates in the presence of [Rh2{(S)-mepy}4].
DOI : 10.1016/j.tetasy.2005.04.006
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