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  • Title: Iodoalkoxylation of 1,5-anhydro-2-deoxy-hex-1-enitols (glycals).
    Author: Horton D, Priebe W, Sznaidman M.
    Journal: Carbohydr Res; 1990 Sep 19; 205():71-86. PubMed ID: 2276153.
    Abstract:
    Exclusive trans-addition is observed in the iodoalkoxylation of the 6-membered cyclic enol ethers 3,4-di-O-acetyl-L-rhamnal (1), 3,4-di-O-acetyl-L-fucal (2), and related glycal derivatives. The main products from 1 and from 3,4,6-tri-O-acetyl-D-glucal (3) thus had the alpha-manno configuration. Similarly, alpha-talo products were obtained from 2 in 87-93% yield. The product distribution is not affected by the electronegativity of the 5-substituent. It is concluded that steric factors in the glycal and the nucleophile affect only the step of trans-diaxial opening of the intermediate iodonium ion. Enhanced yields of the desired trans-diaxial products were observed in reactions of glycals having the lyxo configuration when the reactions were conducted in tetrahydrofuran or methanol.
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