1047647-75-5Relevant academic research and scientific papers
Methylarene-based PAH synthesis via domino cyclization of 1, 1-difluoro-1-alkenes
Fuchibe, Kohei,Takao, Go,Takahashi, Hiroki,Ijima, Shiori,Ichikawa, Junji
, p. 2019 - 2029 (2019)
Polycyclic aromatic hydrocarbons (PAHs) containing 4-7 benzene rings were synthesized via a methylarene-based protocol. Trimethyl[2-(trifluoromethyl)allyl]silane was electrophilically benzylated with Ar1CH2Br (prepared from Ar1CH3) to afford 2-trifluoromethyl-1-alkenes that were in turn nucleophilically benzylated with Ar2CH2Li (prepared from Ar2CH3) through an SN2-type reaction to produce 1, 1-difluoroethylenes, which are cyclization precursors bearing two 2-arylethyl groups. Magic acid efficiently promoted the domino FriedelCrafts-type cyclization of these precursors, followed by dehydrogenation that enabled the connection among two aryl groups (Ar1 and Ar2) by forming two benzene rings between them, facilitating the synthesis of the desired higher-order PAHs. With the proposed protocol, the combination of even a limited number of methylarenes can yield a variety of PAHs in diverse configurations.
Domino Friedel-crafts-type cyclizations of difluoroalkenes promoted by the α-cation-stabilizing effect of fluorine: An efficient method for synthesizing angular PAHs
Fuchibe, Kohei,Jyono, Hideharu,Fujiwara, Masaki,Kudo, Takao,Yokota, Misaki,Ichikawa, Junji
, p. 12175 - 12185 (2011/12/01)
In order to synthesize polycyclic aromatic hydrocarbons with nonlinear arrangements (angular PAHs), acid-promoted domino cyclizations of 1,1-difluoroalk-1-enes and 1,1-difluoroalka-1,3-dienes were studied. 1,1-Difluoroalkenes, each bearing two aryl substituents, were regioselectively protonated with FSO3H·SbF5 to generate fluorine-stabilized carbocations, which readily underwent domino Friedel-Crafts-type cyclizations to give carbocycles based on 6/n/m/6 ring systems (n,m=5-7) in good to high yields. Protonation of 1,1-difluoroalka-1,3- dienes took place at their electron-rich methylene (CH2) carbon atoms in the presence of milder acids such as camphorsulfonic acid and trifluoromethanesulfonic acid. Domino cyclizations of the resulting fluorine-stabilized allylic carbocations afford carbocycles based on 6/6/6/6 or 6/6/5/6 ring systems in high yields.
Efficient helicene synthesis: Friedel-crafts-type cyclization of 1,1-difluoro-1-alkenes
Ichikawa, Junji,Yokota, Misaki,Kudo, Takao,Umezaki, Satoshi
supporting information; experimental part, p. 4870 - 4873 (2009/02/08)
(Chemical Equation Presented) The unique properties of fluorine substituents, leaving groups that also stabilize an a carbocation, are exploited in a high-yielding synthesis of substituted [4]- to [6]helicenes in three or four steps from commercially available compounds: Two fused benzene rings are constructed in the title reaction of readily prepared 1,1-difluoro-1-alkenes containing two aryl groups followed by dehydrogenation (see scheme).
