title: Synthesis and self-aggregation of cyclic alkynes containing helicene.
abstract: [structure: see text]. All stereoisomers of a cyclic alkyne containing three helicene units, 1,12-dimethylbenzo[c]phenanthrene, are synthesized using a building block. Isomeric [3 + 3]cycloalkynes aggregate in organic solvents. Vapor pressure osmometry reveals dimer formation of (M,M,M)-[3 + 3]cycloalkynes in chloroform and benzene at concentrations above 2 mM. No higher aggregation is observed. The chirality of helicenes plays an important role in self-aggregation, and diastereomeric (M,P,M)-[3 + 3]cycloalkyne forms a dimer only above 15 mM. Aggregation of racemic (M,M,M)-[3 + 3]cycloalkyne or (M,P,M)-[3 + 3]cycloalkyne is much weaker than that of a single enantiomer.
authors.affiliation: Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Okubo
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D011083:Polycyclic Compounds; C031660:helicenes