title: Origin of stereocontrol in the construction of the 12-oxatricyclo[6.3.1.0(2,7)]dodecane ring system by Prins-pinacol reactions.
abstract: Polycyclic products containing the 12-oxatricyclo[6.3.1.0(2,7)]dodecane moiety having either the trans (8a-e) or cis (9a-e) relative configuration of the oxacyclic bridge and the cis angular substituents are formed stereospecifically by Prins-pinacol cyclizations of unsaturated alpha-dithianyl acetals 14a-e or 15a-e. These results show that the topography (boat or chair) of the Prins cyclization of the sulfur-stabilized oxocarbenium ions generated from acetals 14a-e or 15a-e is controlled by the stereoelectronic influence of the allylic substituents, with steric effects playing a minor role. A complex molecular rearrangement that is terminated by a thio-Prins-pinacol reaction is also identified.
authors.affiliation: Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, California 92697-2025, USA. leoverma@uci.edu
authors.forename: Larry E
authors.initials: LE
authors.lastname: Overman
authors.forename: Paul S
authors.initials: PS
authors.lastname: Tanis
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D003500:Cyclization; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D015394:Molecular Structure; D011083:Polycyclic Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C548183:12-oxatricyclo(6.3.1.0(2,7))dodecane; D000473:Alkanes; D006575:Heterocyclic Compounds, 3-Ring; D011083:Polycyclic Compounds; C007548:n-dodecane