Titanocene dichloride reduction

Though the usual product of epoxide reductions is the alcohol (10-85), epoxides are reduced all the way to the alkane by titanocene dichloride and Et3SiH-BH3. ... 

Reduction of carboxylic esters with titanocene dichloride... 

The XeChlor process is a reductive dechlorination process for the treatment of a wide array of organic halides, including conversion of polychlorinated biphenyls (PCBs) into biphenyl or dioxins into simple dibenzofuran. The dechlorination catalyst is prepared in situ from titanocene dichloride sodium borohydride is the reducing agent. 

Reduction of carboxylic acids 9-42 Reduction of carboxylic esters 9-43 Reduction of carboxylic esters with titanocene dichloride 9-44 Reduction of anhydrides 9-45 Reduction of acyl halides 9-53 Reduction of nitriles 9-57 Reduction of hydroperoxides 9-60 Reduction of peroxides 9-69 Reaction between aldehydes and base (Cannizzaro)... 

The cyclisation of alkenes by low valent titanium has also been applied to intramolecular processes. Thus the reduction of titanocenes bearing pendant alkenyl substituents [TiCl2(r -C5Me4XCH = CHR)2] (X = SiMe2, CH2, CHMe R = H, Me) provides chiral titanacyclopentanes shown in Scheme 2.16 The titan-acyclopentanes could then be cleaved with HC1 to provide new titanocene dichlorides in which the two cyclopentadienyl ligands were linked by a hydrocarbon chain. 

Magdesieva, T.V., Graczyk, M., Vallat, A., Nikitin, O.M., Demyanov, P.I., Butin, K.P. and Vorotyntsev, M.A. (2006) Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides. Electrochim. Acta 52, 1265-1280. 

As a rather special case, alkyl aldehydes are reduced with titanocen dichloride to the hydrocarbons through a titanium-bonded alkenic intermediate as shown by a deuterium-labeling experiment. Thus, dodecanal was converted to dodecane in 71% yield, along with dodecan-I-ol in 15-20% yield alkyl ketones such as adamantan-2-one and dodecan-6-one afforded alcohols as the major products. No reduction occurred in the case of aryl aldehydes where alkene formation is impossible. ... 

For example, titanocene dichloride affords the two-electron reduction of activated ketones into alcohols [93]. 

Titanium(IV) chloride and titanocene dichloride have catalytic effects on the reduction, e.g., in the transformation of alkyl thiocyanates to dialkyl disulfides and nitroarenes to aryl amines, respectively. 

Titanocene dichloride catalyzes the reduction of alkyl, aryl, and vinyl bromides, aryl chlorides, alkoxy- and halosilanes ketones, esters, and carboxylic acids with alkyl Grignard reagents. This Cp2TiCl2/RMgX system can also be used for the hydromagnesation of alkynes, dienes, and alkenes (Section 3.2.5). Kambe et al. have reported a new type of titanocene-catalyzed transformation with vinyl Grignard reagents and chlorosilanes to furnish l,4-disilyl-2-butenes, as shown in Scheme 3.43 [31]. 

Catalytic transformations circumventing this problem have been realized by protonation of titanium oxygen and carbon bonds in the presence of 2,4,6-collidine hydrochloride and a stoichiometric reducing agent, usually zinc or manganese. The reaction conditions for the reductive opening in the presence of 5 mol% titanocene dichloride are depicted in Scheme 24 [41]. 

Reduction of halides. The reaction of titanocene dichloride with magnesium under argon at 0° generates an active reducing agent. Azo compounds are reduced by this reagent to hydrazo compounds in about 75% yield. Alkyl... 

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