Fe(<scp>ii</scp>)-Catalyzed alkenylation of benzylic C–H bonds with diazo compounds
作者:Jiang-Ling Shi、Qinyu Luo、Weizhi Yu、Bo Wang、Zhang-Jie Shi、Jianbo Wang
DOI:10.1039/c9cc01060b
日期:——
We report herein an alkenylation of benzylic C(sp3)–H bonds with diazocompounds via carbon cation intermediates with DDQ as the oxidant in the presence of a catalytic amount of Fe(II). Diphenylmethane, toluene, benzyl methyl sulfide and their derivatives could be applied as substrates to afford the tetra-substituted olefin products, which may serve as useful building blocks in organic synthesis.
In the presence of titanium tetrachloride and pyridine in THF, diethyl malonate undergoes condensation with aliphatic and aromatic ketones. The yields of the resulting α,β-unsaturated compounds are good even in cases, where other condensation methods are unsuccessful. Products, resulting from α-mono-, α,α-, α,α′-di- and α,α,α-trihalogeno ketones are probably of special interest as useful intermediates
(Hexaphenyltrimethylene)methane Dication and Related Carbocations
作者:Nicholas J. Head、George A. Olah、G. K. Surya Prakash
DOI:10.1021/ja00150a017
日期:1995.11
By ionization of the respective alkenediol (8a), the (hexaphenyltrimethylene)methane dication (2) has been prepared and found stable in solution under superacidic stable ion conditions (FSO3H/SO2ClF) up to at least -20 degrees C. The spectroscopic data and AM1 theoretical modeling indicate that although the entire pi-system is twisted, phenyl groups stabilize the positive charges in 2 to a similar degree as those in the trityl cation. The hexa-p-CF3 derivative of 2 was also observable but only at very low temperatures (-90 degrees C). Disruption of the 3-fold symmetry and reduction of the number of stabilizing phenyl rings even to five resulted in intramolecular allylation and subsequent formation of the corresponding indenyl cations. In all the cases studied no evidence for ''Y-aromatic'' stabilization was found.