title: Efficient syntheses of thiochromans via cationic cycloadditions.
abstract: alpha-(Benzotriazolyl)methyl thioethers 1a-e reacted with styrenes under Lewis acid catalysis to give novel polysubstituted thiochromans (3,4-dihydro-2H-1-benzothiopyrans) 3-14 and 16-20 in generally high yields. Most thiochromans were isolated as one diastereomer following recrystallization. The configuration and conformation of the products are predicted on the basis of their NMR data. A stepwise reaction, proceeding via a [4(+) + 2] cationic polar cycloaddition mechanism, is proposed.
authors.affiliation: Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, 32611-7200, USA. katrizky@chem.ufl.edu
authors.forename: A R
authors.initials: AR
authors.lastname: Katritzky
authors.forename: M A
authors.initials: MA
authors.lastname: Button
mesh_terms: D000893:Anti-Inflammatory Agents / Q000138:chemical synthesis* / Q000737:chemistry; D000928:Antidepressive Agents / Q000138:chemical synthesis / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D002839:Chromans / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation
chemical_list: D000893:Anti-Inflammatory Agents; D000928:Antidepressive Agents; D002412:Cations; D002839:Chromans