title: A versatile synthesis of functionalized pentahelicenes.
abstract: A general synthetic methodology for the preparation of functionalized (hetero)helicenes has been developed. It employs the sequence of a double propargyl organometallics (Li, Mg, Ga/In) addition to a tolan-2,2'-dialdehyde-type intermediate, a cobalt-catalyzed/cobalt-mediated [2 + 2 + 2] cycloisomerization of a triyne intermediate, and a double silica gel-assisted acetic acid elimination to receive pentahelicene, 1,14-diazapentahelicene, and 3,12-dichloro-, 3,12-dichloro-7-trimethylsilyl-, and 3,12-di-tert-butylpentahelicene. 3,12-Dichloropentahelicene undergoes a Suzuki-Miyaura coupling with aryl boronic acids (or ester) under palladium catalysis to afford 3,12-diarylpentahelicenes.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.
authors.forename: Olivier
authors.initials: O
authors.lastname: Songis
authors.forename: Jirí
authors.initials: J
authors.lastname: Mísek
authors.forename: Markus B
authors.initials: MB
authors.lastname: Schmid
authors.forename: Adrian
authors.initials: A
authors.lastname: Kollárovic
authors.forename: Irena G
authors.initials: IG
authors.lastname: Stará
authors.forename: David
authors.initials: D
authors.lastname: Saman
authors.forename: Ivana
authors.initials: I
authors.lastname: Císarová
authors.forename: Ivo
authors.initials: I
authors.lastname: Starý
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D003500:Cyclization; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D009942:Organometallic Compounds; D011083:Polycyclic Compounds; C031660:helicenes