Reductive openings of benzylidene acetals. Kinetic studies of borane and alane activation by Lewis acids.

Summary, in English

The reaction kinetics for a number of reductive openings of methyl 2,3-di-O-benzyl-4,6-O-benzylidene-alpha-d-glucopyranoside have been investigated. Openings to give free HO-6 (using BH(3).THF-AlCl(3)-THF or LiAlH(4)-AlCl(3)-Et(2)O) follow first order kinetics, while reactions yielding free HO-4 (using BH(3).NMe(3)-AlCl(3)-THF or BH(3).NMe(3)-BF(3).OEt(2)-THF) follow higher order kinetics. The addition of water to the BH(3).NMe(3)-AlCl(3)-THF results in faster reactions. The BH(3).SMe(2)-AlCl(3)-THF system constitutes a borderline case, yielding both free HO-6 (by a first order reaction) and free HO-4 (by a higher order reaction). These results correlate well with the concept of regioselectivity by activation of borane complexes.

• Author: Richard Johnsson; Risto Cukalevski; Fanny Dragén; Damir Ivanisevic; Ida Johansson; Linn Petersson; Erika Elgstrand Wettergren; Ka Bo Yam; Beatrice Yang; Ulf Ellervik
• Department/s: Centre for Analysis and Synthesis; Department of Immunotechnology
• Publishing year: 2008
• Language: English
• Pages: 2997-3000
• Publication/Series: Carbohydrate Research
• Volume: 343
• Links: http://dx.doi.org/10.1016/j.carres.2008.08.022
• Document type: Journal article
• Publisher: Elsevier
• Topic: Organic Chemistry; Immunology in the medical area
• Status: Published
• ISBN/ISSN/Other: ISSN: 1873-426X