Carbon-Carbon Bond Formation by Reductive Coupling with Titanium(II) Chloride Bis(Tetrahydrofuran)* John J
Carbon-Carbon Bond Formation by Reductive Coupling with Titanium(II) Chloride Bis(tetrahydrofuran)* John J. Eisch**, Xian Shi, Jacek Lasota Department of Chemistry, The State University of New York at Binghamton, Binghamton, New York 13902-6000, U.S.A. Dedicated to Professor Dr. Dr. h. c. mult. Günther Wilke on the occasion of his 70th birthday Z. Naturforsch. 50b, 342-350 (1995), received September 20, 1994 Carbon-Carbon Bond Formation, Reductive Coupling, Titanium(II) Chloride, Oxidative Addition, Carbonyl and Benzylic Halide Substrates Titanium(II) bis(tetrahydrofuran) 1, generated by the treatment of TiCl4 in THF with two equivalents of n-butyllithium at -78 °C, has been found to form carbon-carbon bonds with a variety of organic substrates by reductive coupling. Diphenylacetylene is dimerized to ex clusively (E,E)-1,2,3,4-tetraphenyl-l,3-butadiene; benzyl bromide and 9-bromofluorene give their coupled products, bibenzyl and 9,9'-bifluorenyl, as do benzal chloride and benzotrichlo- ride yield the l,2-dichloro-l,2-diphenylethanes and l,l,2,2-tetrachloro-l,2-diphenylethane, respectively. Styrene oxide and and ris-stilbene oxide undergo deoxygenation to styrene and fra/«-stilbene, while benzyl alcohol and benzopinacol are coupled to bibenzyl and to a mix ture of tetraphenylethylene and 1,1,2,2-tetraphenylethane. Both aliphatic and aromatic ke tones are smoothly reductively coupled to a mixture of pinacols and/or olefins in varying proportions. By a choice of experimental conditions either the pinacol or the olefin could be made the predominant product in certain cases. The reaction has been carried out with heptanal, cyclohexanone, benzonitrile, benzaldehyde, furfural, acetophenone, benzophenone and 9-fluorenone.
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