کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1390995 983172 2006 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
On the regioselectivity of the Hanessian–Hullar reaction in 4,6-O-benzylidene protected galactopyranosides
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
On the regioselectivity of the Hanessian–Hullar reaction in 4,6-O-benzylidene protected galactopyranosides
چکیده انگلیسی

The N-bromosuccinimide mediated fragmentation of methyl 4,6-O-benzylidene-β-d-galactopyranoside results in the formation of methyl 4-O-benzoyl-6-bromo-6-deoxy-β-d-galactopyranoside and methyl 4-O-benzoyl-3-bromo-3-deoxy-β-d-gulopyranoside, as opposed to the methyl 6-O-benzoyl-3-bromo-3-deoxy-β-d-gulopyranoside originally reported. The kinetic methyl 4-O-benzoyl-6-bromo-6-deoxy-β-d-galactopyranoside rearranges to the thermodynamic methyl 4-O-benzoyl-3-bromo-3-deoxy-β-d-gulopyranoside under the reaction conditions, likely via a 3,6-anhydro galactopyranoside. The NBS-mediated cleavage of 4,6-O-benzylidene acetals in the galactopyranoside series is therefore shown to conform to the regiochemistry observed in the corresponding gluco- and mannopyranoside series with preferential cleavage of the C6–O6 bond by an ionic mechanism.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Research - Volume 341, Issue 10, 24 July 2006, Pages 1748–1752
نویسندگان
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