title: Tosvinyl and besvinyl as protecting groups of imides, azinones, nucleosides, sultams, and lactams. Catalytic conjugate additions to tosylacetylene.
abstract: The use of the 2-(4-methylphenylsulfonyl)ethenyl (tosvinyl, Tsv) group for the protection of the NH group of a series of imides, azinones (including AZT), inosines, and cyclic sulfonamides has been examined. The Tsv-protected derivatives are obtained in excellent yields by conjugate addition to tosylacetylene (ethynyl p-tolyl sulfone). The stereochemistry of the double bond can be controlled at will: with only 1 mol % of Et3N or with catalytic amounts of NaH, the Z stereoisomers are generated almost exclusively, while the E isomers are obtained using a stoichiometric amount of DMAP. Analogous phenylsulfonylvinyl-protected groups (with the besvinyl or Bsv group instead of Tsv) are obtained stereospecifically by reaction with (Z)- or (E)-bis(phenylsulfonyl)ethene. For lactams and oxazolidinones, this last method is much better. The Tsv and Bsv groups are stable in the presence of non-nucleophilic bases and to acids. They can be removed highly effectively via a conjugate addition-elimination mechanism using pyrrolidine or sodium dodecanethiolate as nucleophiles.
authors.affiliation: Departament de Química Orgànica, Facultat de Química, Universitat de Barcelona , Diagonal 645, 08028 Barcelona, Catalonia, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Petit
authors.forename: Lluís
authors.initials: L
authors.lastname: Bosch
authors.forename: Joan
authors.initials: J
authors.lastname: Font
authors.forename: Laura
authors.initials: L
authors.lastname: Mola
authors.forename: Anna M
authors.initials: AM
authors.lastname: Costa
authors.forename: Jaume
authors.initials: J
authors.lastname: Vilarrasa
mesh_terms: D002384:Catalysis; D007094:Imides / Q000737:chemistry*; D007769:Lactams / Q000737:chemistry*; D015394:Molecular Structure; D009705:Nucleosides / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*; D014105:Tosyl Compounds / Q000737:chemistry
chemical_list: D007094:Imides; D007769:Lactams; D009705:Nucleosides; D011759:Pyrrolidines; D013449:Sulfonamides; D014105:Tosyl Compounds; C480101:beta-sultam