Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe

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Abstract
Carbocyclic Compounds from Monosaccharides. 1. Transformations in the Glucose SeriesA method for the preparation of pentasubstituted cyclopentanes from monosaccharides is presented, involving two crucial steps, viz. the reductive fragmentation of 5‐bromo‐5‐deoxyglucosides (such as 10, 17 and 23, see Scheme 3) with Zn or butyl lithium yielding 5,6‐dideoxy‐hex‐5‐enoses (such as 11 and 24, see Schemes 3 and 4), and the subsequent cyclization of these hexenoses with N‐methyl‐ or N‐(alkoxyalkyl)hydroxylamines (via the corresponding nitrones) to form cyclopentano‐isoxazolidines (see Scheme 2). Thus, the glucosides 17 and 23 were converted diastereoselectively and in good yields into the cyclopentano‐isoxazolidines 27 and 45 (Schemes 5 and 7), which were characterized by their transformation into various derivatives. 27 and 45 were correlated through the common derivative 62. The configuration of the cyclization products were established by pyrolysis of the N‐oxide 65 to the enol ether 67 (Scheme 10).