143901-94-4Relevant academic research and scientific papers
Synthesis of substituted helicenes by Ir-catalyzed annulative coupling of biarylcarboxylic acid chlorides with alkynes
Kamikawa, Ken,Den, Hiroakira,Tsurusaki, Akihiro,Nagata, Tomoya,Miura, Masahiro
supporting information, p. 1069 - 1074 (2018/07/29)
A series of substituted [4] and [5]helicenes were synthesized in moderate to good yields by an Ir-catalyzed annulative coupling of biarylcarboxylic acid chlorides with internal alkynes, which involves facile C-H bond cleavage and decarbonylation. The double annulative coupling of 1, 1′:5′, 1″-ternaphthalene- 2, 2″-dicarboxylic acid dichloride with 4-octyne was also accomplished to give rise to an S-shaped double helicene. Unexpectedly, a π-extended benzofluoranthene-merged [5]- helicene was constructed through the annulative coupling and the successive C(aryl)-C(aryl) bond forming reaction when 1, 1′:4′, 1″-ternaphthalene-2, 2″-dicarboxylic acid dichloride was employed as the substrate. The crystal structure and the optical properties of the latter unique product were also investigated.
Exploiting the π-acceptor properties of carbene-stabilized phosphorus centered trications [L3P] 3+: Applications in Pt(II) catalysis
Carreras, Javier,Patil, Mahendra,Thiel, Walter,Alcarazo, Manuel
, p. 16753 - 16758,6 (2012/12/13)
Reaction of tris(dimethylaminocyclopropenium) substituted phosphine 1 with K2PtCl4 afforded the bench stable complex 3 which upon treatment with Ag[CB11H6Cl6] turned out to be an excellent catalyst for the transformation of a variety of ortho-biaryl substituted alkynes into polycyclic homo- and heteroarenes of different size, shape, and curvature through a 6-endo-dig cyclization. This constitutes the first example ever reported of using a P1-centered trication as ligand in catalysis. The strong π-acceptor character of 1 that derives from its three positive charges substantially increases the intrinsic π-acidity of Pt in complex 1?PtCl2 and dramatically enhances its ability to activate π-systems toward nucleophilic attack. As a consequence, a remarkable acceleration of the model transformation is observed when compared with other classical π-acceptor ligands such as P(OPh)3 or P(C 6F5)3. Moreover, the employment of 1 as ligand also expands the scope of this reaction to previously inaccessible substitution patterns. Kinetic studies and deuterium labeling experiments as well as density functional theory (DFT) calculations were performed in order to explain these findings.
