Ketones titanium chloride-magnesium

Solutions of low-valence titanium chloride (titanium dichloride) are prepared in situ by reduction of solutions of titanium trichloride in tetrahydrofuran or 1,2-dimethoxyethane with lithium aluminum hydride [204, 205], with lithium or potassium [206], with magnesium [207, 208] or with a zinc-copper couple [209,210]. Such solutions effect hydrogenolysis of halogens [208], deoxygenation of epoxides [204] and reduction of aldehydes and ketones to alkenes [205,... 

A combination of alkali metal salts, particularly potassium chloride, with low-valent titanium reagents generated from titanium chlorides with lithium or magnesium in either THF or DME are effective reagents for stereoselective McMurry coupling reactions of aldehydes and ketones to substituted alkenes (Figure 1.11). 

On the other hand, the predominant formation of the diastereomeric aldols 3 b results from the titanium enolate 1 b of (S )-5,5-dimethyl-4-tert-butyldimethylsilyloxy-3-hexanone. For this purpose, the ketone is first deprotonated with A-(bromomagnesio)-2,2,6,6-tetramethylpiperidine and the magnesium enolate, presumably (E) configurated, formed is thereby treated with hexamethylphosphoric triamide and triisopropyloxytitanium chloride. After sonification, the aldehyde is added to give predominantly aldol adducts 3b the diastereomeric ratio of 3b/2b surpasses 95 5 and the chemical yields range from 85 to 88%53b. 

CARBONIC ACID, LITHIUM SALT (554-13-2) LijCOj Aqueous solution is an organic base. Violent reaction with acids. Inconpatible with fluorine, germanium, lead diacetate, magnesium, mercurous chloride, silicon, silver nitrate, titanium. Aqueous solution incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cellulose nitrate, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, isocyanates, ketones, glycols, nitrates, phenols, vinyl acetate. Exothermic decomposition with maleic anhydride. Corrodes aluminum, copper, zinc in the presence of moisture. On small fires, use any extinguishing agent. 

More work has been reported on the inter- and intra-molecular pinacolic coupling of aldehydes and ketones, e.g. cycloheptanone and acetone gave (220) on treatment with a magnesium-mercury-titanium(iv) chloride reagent. ... 

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