title: Highly stereoselective construction of spiro[4.5]decanes by SmI(2)-promoted ketyl radical mediated tandem cyclization.
abstract: [reaction: see text] Ketyl radical mediated tandem cyclization of omega-alkynyl carbonyl compounds bearing activated alkene using SmI(2) gave spiro[4.5]decanes stereoselectively. In the presence of HMPA, alpha,beta-unsaturated esters and alkenyl phosphonates were converted to spiro[4.5]decanes and a monocyclic compound, respectively. In the presence of Sm, bicyclic lactones were obtained from alpha,beta-unsaturated esters. The spiro[4.5]decane was provided from an alkenyl phosphonate. Interestingly, the stereochemical changeover at the first cyclization has been controlled by means of a variety of activators.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science (RIKADAI), 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Inui
authors.forename: Atsuo
authors.initials: A
authors.lastname: Nakazaki
authors.forename: Susumu
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D000473:Alkanes / Q000138:chemical synthesis*; D000475:Alkenes / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry; D001643:Bridged Bicyclo Compounds / Q000737:chemistry; D003500:Cyclization; D004952:Esters / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D007783:Lactones / Q000737:chemistry; D008956:Models, Chemical; D063065:Organophosphonates / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D000473:Alkanes; D000475:Alkenes; D000480:Alkynes; D001643:Bridged Bicyclo Compounds; D004952:Esters; D005609:Free Radicals; D007783:Lactones; D063065:Organophosphonates; D013141:Spiro Compounds; C012867:decane