21473-01-8Relevant articles and documents
1-Naphthyltropylium Ions Having Condensed Aromatic Rings at the 8-Position: Dependence of the Intramolecular Charge-Transfer Interaction upon Gemetry of the Donor
Tsuji, Ryotaro,Komatsu, Koichi,Inoue, Yoichiro,Takeuchi, Ken'ichi
, p. 636 - 641 (1992)
A series of 1-aryl-8-tropylionaphthalene cations (aryl = 1-naphthyl (8a), 2-naphthyl (8b), 1-pyrenyl (8c), and 2-pyrenyl (8d) have been synthesized, in which the condensed aromatic system and a tropylium ring are placed at a face-to-face arrangement.The 1H NMR spectra of these cations exhibit remarkable upfield shift for the tropylium ring protons in accord with such molecular geometry; this geometry is further supported by theoretical calculations both by MMP2 and by AM1.The cations 8a-d show the intramolecular charge-transfer (CT) band at 510 (sh) (8a), 525 (sh) (8b), 585 (8c), and 600 (sh) nm (8d) in dichloromethane, indiacting a correlation of the CT transition energy with the donor's ionzation potential regardless of the relative geometry with the acceptor.In contrast, the indicies of cation's thermodynamic stability, pKR+ (6.27 for 8a, 5.45 for 8b, 6.28 for 8c, and 5.75 for 8d), and reduction potential (-0.649 V vs Ag/Ag+ for 8a, -0.601 for 8b, -0.665 for 8c, and -0.625 V for 8d) are highly dependent on the mutual geometry of donor and acceptor, reflecting the effectiveness in overlap of donor's HOMO and acceptor's LUMO.
Stereodivergent Construction of Vicinal Acyclic Quaternary-Tertiary Carbon Stereocenters by Michael-Type Alkylation of α,α-Disubstituted N- tert-Butanesulfinyl Ketimines
Liu, Hui,Lu, Chong-Dao,Yao, Yun,Yisimayili, Nuermaimaiti
supporting information, p. 7450 - 7455 (2021/10/02)
Vicinal quaternary-tertiary carbon stereocenters were constructed with excellent stereoselectivity via aza-enolization of enantioenriched acyclic N-tert-butanesulfinyl ketimines bearing two sterically similar α-linear alkyl substituents followed by conjugate addition to nitroalkenes. Further changes of the absolute configuration of the sulfinyl group and/or the α-stereocenter in the ketimine allowed the facile stereodivergent synthesis of all four diastereomers of the Michael-type alkylation adducts. This reaction is a successful example of acyclic stereocontrol based on stereoselective α-deprotonation for the formation of fully substituted aza-enolates from ketone derivatives.
Bismuth-catalyzed synthesis of polycyclic aromatic hydrocarbons (PAHs) with a phenanthrene backbone via cyclization and aromatization of 2-(2-arylphenyl)vinyl ethers
Murai, Masahito,Hosokawa, Naoki,Roy, David,Takai, Kazuhiko
supporting information, p. 4134 - 4137 (2014/09/30)
The reaction of 2-(2-arylphenyl)vinyl ethers in the presence of a catalytic amount of bismuth(III) triflate gave substituted phenanthrenes in excellent yields under mild reaction conditions. The reaction was also applied to the construction of other polycyclic aromatic hydrocarbons (PAHs), such as chrysene, helicene, and pyrene having a phenanthrene backbone, via regioselective cyclization. This method has the advantages of easy availability of the cyclization precursors, operational simplicity, and high reaction efficiency.
