CYCLOADDITION OF TRICHLOROACETYL ISOCYANATE TO GLYCALS

Article abstract of DOI:10.1016/0008-6215(87)80275-6

Cycloaddition of trichloroacetyl isocyanate to 1,5-anhydro-2-deoxy-D-erythro- and -L-threo-pent-1-enitols, and 1,5-anhydro-2-deoxy-D- and -L-arabino-hex-1-enitols having benzyl, methyl, tert-butyldimethylsilyl, and trimethylsilyl substituents on hydroxyl groups proceeds satisfactorily, under normal pressure at room temperature, to give a mixture of <2 + 2> and <4 + 2> cycloadducts.The isocyanate enters the glycal molecule stereospecifically anti with respect to the C-3 substituent.Bicyclic adducts slowly rearrange to the respective α,β-unsaturated amides.N-Deprotection of the trichloroacetyl substituent in <2 + 2> cycloadducts produces stable β-lactams.Further deprotection gives crystalline, water-soluble 2-carboxy-2-deoxypento- and -hexo-pyranosylaminolactams having a unique bicyclic sugar structure.