title: Biocatalytic route to C-3'-azido/-hydroxy-C-4'-spiro-oxetanoribonucleosides.
abstract: The lipase, Novozyme(®)-435, exclusively deacetylates the 5-O-acetyl over 4-C-acetyloxymethyl group of almost identical reactivity in 5-O-acetyl-4-C-acetyloxymethyl-3-azido-3-deoxy-1,2-O-isopropylidene-α-D-ribofuranose that led to the development of first and efficient synthesis of 3'-azido-/3'-amino-C-4'-spiro-oxetanoribonucleosides T, U, C and A in 20-24% overall yields. The X-ray study on the compound obtained by tosylation of lipase-mediated monodeacetylated product unambiguously confirmed the point of diastereoselective monodeacetylation on diacetoxy-azido-ribofuranose derivative. The capability of Novozyme(®)-435 for selective deacylation of 5-O-acetyl group in 5-O-acetyl-4-C-acetyloxymethyl-3-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranose recently discovered by us has been successfully used for the synthesis of C-4'-spiro-oxetanoribonucleosides A and C in good yields. These results clearly indicate that the broader substrate specificity and highly selective capability of Novozyme(®)-435 for carrying out acetylation/deacetylation reactions can be utilized for the development of environment friendly selective methodologies in organic synthesis.
authors.affiliation: Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi 110 007, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi 110 007, India; Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: Vivek K
authors.initials: VK
authors.lastname: Sharma
authors.affiliation: Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi 110 007, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi 110 007, India. Electronic address: ashokenzyme@gmail.com.
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Prasad
mesh_terms: D000215:Acylation; D001386:Azides / Q000138:chemical synthesis*; D055162:Biocatalysis; D018360:Crystallography, X-Ray; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005656:Fungal Proteins; D055772:Green Chemistry Technology; D008049:Lipase / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry*; D012263:Ribonucleosides / Q000138:chemical synthesis*; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D001386:Azides; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D009844:Oligosaccharides; D012263:Ribonucleosides; D013141:Spiro Compounds; C093667:Novozyme 435; D008049:Lipase
keywords: Azido-spironucleosides; Biocatalysis; Diastereoselectivity; Lipase; Novozyme(®)-435