title: Influence of the -CH2X substituent on the regioselectivity of intramolecular meta-photocycloaddition reactions.
abstract: In studies related to the synthesis of the bicyclo[3.2.1]octane core of enterocin by an intramolecular meta-photocycloaddition, it was found that the regioselectivity of the reaction depends strongly on the substituent -CH2X in the ortho-position to the tether. Electropositive groups X (X = H, Me, TMS, TES) gave preferentially the linear isomer (regioisomeric ratio = 87/13 to >95/5), whereas electronegative substituents (X = OH, OAc, F) showed a clear preference for the angular isomer (regioisomeric ratio = 75/25 to >95/5). The silylated and fluorinated products were obtained as single isomers in moderate yield.
authors.affiliation: Lehrstuhl für Organische Chemie I, Technische Universität München , Lichtenbergstr. 4, 85747 Garching, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Wegmann
authors.forename: Thorsten
authors.initials: T
authors.lastname: Bach
mesh_terms: D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009795:Octanes / Q000138:chemical synthesis* / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D001643:Bridged Bicyclo Compounds; D009795:Octanes; C000590000:bicyclo(2.2.2)octane