Substituent dependence of the diastereofacial selectivity in iodination and bromination of glycals and related cyclic enol ethers

…, C Chiappe, A De Rubertis, MF Ruasse

Index: Boschi; Chiappe; De Rubertis; Ruasse Journal of Organic Chemistry, 2000 , vol. 65, # 25 p. 8470 - 8477

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Citation Number: 36

Abstract

The stereochemical course of the electrophilic iodination and bromination of tri-O-benzyl-d- glucal under various conditions has been compared to that of substituted dihydropyrans 2-5. IN3 addition in acetonitrile affords trans-α-iodoazides (80-87%), besides small amounts of trans-β-adducts, in the presence or the absence of benzyloxy substituents at C-3 or C-4, and in agreement with bridged iodonium ion intermediates. In contrast, the diastereofacial ...