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- Title
Aldehyde-Promoted Addition of 2-(Trimethylsilyl)thiazole to α,α′-Dialkoxy Ketones: A new way to branched-chain monosaccharides.
- Authors
Carcano, Michela; Vasella, Andrea
- Abstract
The reaction of 2-(trimethylsilyl)thiazole (2-TST) with several ketones was tested in the presence or absence of aldehydes. The keto aldehyde 5 ( Scheme 2) was prepared from 1 via the hydroxy aldehyde 4 in 3 steps. It reacted with 2-TST to give, after desilylation and acetylation, the bis-thiazole 6. The ketone 11, obtained from 4 in 3 steps, reacted with 2-TST to give, after desilylation, 12. The ketofuranose 17 ( Scheme 3) reacted with 2-TST to yield exclusively the more stable D- gluco epimer 18. The reaction of the ketone 11 ( Scheme 2) with 2-TST was faster in the presence of 1 equiv. of the keto aldehyde 5, suggesting that an aldehyde promotes the indirect and intermolecular addition of 2-TST to a ketone. We have studied the effect of several aldehydes on the rate of the reaction of the ketones 11 and 17 with 2-TST at different temperatures and at different concentrations of the ketones and of the aldehydes. Electrophilic aldehydes, and particularly 2-fluorobenzaldehyde (0.1 equiv.), promote the addition of 2-TST to electrophilic ketones.
- Publication
Helvetica Chimica Acta, 1998, Vol 81, Issue 5-8, p889
- ISSN
0018-019X
- Publication type
Article
- DOI
10.1002/hlca.19980810510