Twisted Push-Pull Alkenes Bearing Geminal Cyclicdiamino and Difluoroaryl Substituents.

The systematic combination of N-heterocyclic olefins (NHOs) with fluoroarenes resulted in twisted push-pull alkenes. These alkenes carry electron-donating cyclicdiamino substituents and two electron-withdrawing fluoroaryl substituents in the geminal positions. The synthetic method can be extended to a variety of substituted push-pull alkenes by varying the NHO as well as the fluoroarenes.

Trisubstituted geminal diazaalkene derived transient 1,2-carbodications.

The coulombic repulsion between two adjacent cation centres of 1,2-carbodications is known to decrease with π- and/or n-donor substituents by a positive charge delocalization. Here we report the delocalization of the positive charge of transient 1,2-carbodications having one H-substituent by an intramolecular base-coordination. N-heterocyclic olefin (NHO) derived 2-pyrrolidinyl appended trisubstituted geminal diazaalkenes were used for the generation of transient 1,2-carbodications through a 2-e chemical oxidation process.

Direct ortho-C-H Aminoalkylation of 2-Substituted Pyridine Derivatives Catalyzed by Yttrium Complexes with N,N'-Diarylethylenediamido Ligands.

A mixed ligated amidoyttrium complex, Y(NBn)(L1)(THF) (8, L1 = N, N'-bis(2,6-diisopropylphenyl)ethylenediamine), served as a catalyst for addition of the ortho-pyridyl C(sp)-H bond of 2-substituted pyridines to nonactivated imines; complex 8 showed superior catalytic performance compared with Y[N(SiMe)] (1) and Y[N(SiMe)](NBn)(THF) (2). Concerning the reaction mechanism, we conducted a stoichiometric reaction of an alkylyttrium complex, Y(CHSiMe)(L1)(THF) (7), with 2-ethylpyridine (4e), giving a mixture of (η-pyridylmethyl)yttrium complex 9 and (η-pyridyl)yttrium complex 10 along with elimination of SiMe. Furthermore, addition of N-( tert-butyl)-2-methylpropan-1-imine (5i) to the mixture of 9 and 10 afforded (pyridylmethylamido)yttrium complex 11 as a single product, and the catalytic activity of 11 was comparable to that of complex 8.