[2 + 2] Cycloaddition of trichloroacetyl isocyanate to glycals

✍ Scribed by Marek Chmielewski; Zbigniew Kałuza

• Book ID: 102992377
• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 634 KB
• Volume: 167
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(87)80275-6

✦ Synopsis

Cycloaddition of trichloroacetyl isocyanate to 1,5-anhydro-2-deoxy-Derythro-and -L-three-pent-1-enitols, and 1,5-anhydro-2-deoxy-o-and -L-arabinohex-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 + 21 and [4 + 21 cycloadducts. The isocyanate enters the glycal molecule stereospecifically anti with respect to the C-3 substituent. Bicyclic adducts slowly rearrange to the respective o&unsaturated amides. N-Deprotection of the trichloroacetyl substituent in [2 + 21 cycloadducts produces stable /3-lactams. Further deprotection gives crystalline, water-soluble 2-carboxy-2deoxypento-and -hexo-pyranosylaminolactams having a unique bicyclic sugar structure.