Couplings of Benzylic Halides Mediated by Titanocene Chloride:  Synthesis of Bibenzyl Derivatives

Abstract

Titanocene monochloride catalyzes the homocoupling of benzylic halides and benzylic gem-dibromides to give the corresponding bibenzyl and stilbenyl systems. Exposure of benzylic bromides to Ti(III) in the presence of aldehydes gave rise to the Barbier-type products. Examples of the utility of the herein described processes are included.

Reductive homocoupling of benzylic halides in aqueous medium using recyclable alumina-supported nickel nanoparticles

“…Thus the present Ni-alumina mediated procedure for the homocoupling of diversely substituted benzylic halides comes out with a wider applicability for the synthesis of utilitarian compounds as well as construction of important molecular skeletons. 30 The present Ni-alumina mediated protocol was more costeffective than many of the analogous protocols 12,15,17,20,23,24 appeared so far due to easy accessibility of the requisite components. Moreover, additional metals, ligands and other auxiliary substances were necessary in many reports 11,15,17,18,20,23,24 and the reactions were carried out under inert atmosphere.…”

“…7 These dimeric homocoupling reactions are, in general, mediated by stoichiometric amount of metals, such as vanadium, 8 manganese, 9 cobalt, 10 nickel, 11 indium, 12 and chromium. 13 Several transition metals, such as nickel, 14 palladium complexes, 15 manganese, 16 titanium complex, 17 iron, 18 and cobalt salts 19 and also ionic liquids 20 were developed in last few years as catalysts to prepare dibenzyl compounds. Major drawbacks of many reported processes are associated with the use of expensive, noncommercial and less stable metal catalysts, 15b use of co-metals with main metal catalysts, use of stoichiometric amount of organomagnesium or organozinc reagent, 14,16,18 harsh reaction condition, 14d limited substrate scope and long reaction time.…”

Crystal structure of 1-(2-chlorophenyl)-2-(2-nitrophenyl)ethan-1-ol, C14H12ClNO3

“…Combretastatin is known to inhibits growth of the marine P388 lymphocytic leukemia cell line (PS system), reverses the di erentiation of AC glioma cells into astrocytes and inhibits tubulin polymerization [8,9]. …”

Facile and Efficient Reductive Homocoupling of Benzyl and Aryl Halides Catalyzed by Ionic Liquid [C12mim][CuCl2] in the Presence of Metallic Zinc and Copper

“…However, these above-mentioned protocols, in general, are invariably associated with one or more disadvantages, such as low yields, long reaction times, high reaction temperatures, high catalyst loading, tedious workup procedures, costly metal catalysts, difficulty of catalyst recovery, and environmental toxicity. Reductive coupling reactions using transition metal complexes as catalysts are another important methods for the formation of carbon-carbon bonds, and a variety of reagents, such as palladium [25][26][27][28][29], nickel [30][31][32], iron [33,34], vanadium [35,36], lanthanum [37], zinc [38,39], and other complexes [40][41][42][43][44], have been developed for this conversion. However, most of the procedures still suffered from the use of expensive reagents, difficulties in work up, environmental hazards, and difficulties in recycling of the catalyst.…”