A versatile synthesis of functionalized pentahelicenes.
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.
Songis
Olivier
O
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.
Mísek
Jirí
J
Schmid
Markus B
MB
Kollárovic
Adrian
A
Stará
Irena G
IG
Saman
David
D
Císarová
Ivana
I
Starý
Ivo
I
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
D000480:Alkynes; D009942:Organometallic Compounds; D011083:Polycyclic Compounds; C031660:helicenes