TY - JOUR
T1 - Functionalization of 9-(Dicyanomethylene)fluorene derivatives with substituted acetylenes
AU - Wong, Wai Yeung
AU - Lu, Guo Liang
AU - Choi, Ka Ho
AU - Lin, Zhenyang
N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2003/1
Y1 - 2003/1
N2 - Treatment of (2,7-dibromo-9H-fluoren-9-ylidene)malononitrile (1) with excesses of substituted acetylenes RC ≡ CH [R = Ph, MeC6H4, (η5-C5H5)Fe(η5- C5 H4)] under Sonogashira coupling catalytic conditions afforded novel 9-[cyano(ethynyl)methylene]fluorene derivatives 2-4, respectively, in moderate yields. In these reactions, facile functionalization occurs at the 9-methylene position in the fluorene, one of the cyano groups being substituted by an acetylide moiety. In order to prepare the 2,7-diethynyl-substituted 9-(dicyanomethylene)-fluorene compounds 8-10, palladium-catalyzed coupling reactions between 2,7-dibromofluoren-9-one and RC≡CH in a 1:2 molar ratio first have to be carried out, initially resulting in the formation of compounds 5-7 in good yields. Upon subsequent thermal treatment of 5-7 with malononitrile in DMSO, compounds 8-10 can be isolated in high purity. All attempts to obtain 8-10 from direct coupling of 1 and RC≡CH failed. Single-crystal X-ray structural analyses and density functional calculations have been performed on 3, 4, 7, and 8.
AB - Treatment of (2,7-dibromo-9H-fluoren-9-ylidene)malononitrile (1) with excesses of substituted acetylenes RC ≡ CH [R = Ph, MeC6H4, (η5-C5H5)Fe(η5- C5 H4)] under Sonogashira coupling catalytic conditions afforded novel 9-[cyano(ethynyl)methylene]fluorene derivatives 2-4, respectively, in moderate yields. In these reactions, facile functionalization occurs at the 9-methylene position in the fluorene, one of the cyano groups being substituted by an acetylide moiety. In order to prepare the 2,7-diethynyl-substituted 9-(dicyanomethylene)-fluorene compounds 8-10, palladium-catalyzed coupling reactions between 2,7-dibromofluoren-9-one and RC≡CH in a 1:2 molar ratio first have to be carried out, initially resulting in the formation of compounds 5-7 in good yields. Upon subsequent thermal treatment of 5-7 with malononitrile in DMSO, compounds 8-10 can be isolated in high purity. All attempts to obtain 8-10 from direct coupling of 1 and RC≡CH failed. Single-crystal X-ray structural analyses and density functional calculations have been performed on 3, 4, 7, and 8.
KW - Alkynes
KW - C-C coupling
KW - Cyanides
KW - Density functional calculations
UR - http://www.scopus.com/inward/record.url?scp=0037245039&partnerID=8YFLogxK
U2 - 10.1002/ejoc.200390043
DO - 10.1002/ejoc.200390043
M3 - Journal article
AN - SCOPUS:0037245039
SN - 1434-193X
SP - 365
EP - 373
JO - European Journal of Organic Chemistry
JF - European Journal of Organic Chemistry
IS - 2
ER -