Ketones trichloromethyl, cleavage

The cycloaddition of aldehydes and ketones with ketene under the influence of quinine or quinidine produce chiral 2-oxetanones [46,47]. Solvolytic cleavage of the oxetanone, derived from chloral, and further solvolysis of the trichloromethyl group leads to (5)- and (R)-malic acids with a 98% ee [46] (the chirality of the product depends on the configuration of the catalyst at C-8 and, unlike other alkaloid-induced reactions, it is apparently independent of the presence of the hydroxyl group). No attempts have been made to catalyse the reaction with chiral ammonium salts. 

Halogenated Ketones and Trichloromethyl Triazines It is known that halogenated ketones liberate a Cl radical upon light exposure [45]. Substituted tris-(trichloromethyl)-l,3,5-triazines (10.25) generate a chlorine radical and a carbon-centered radical through the cleavage of a C-Cl bond [46,47] their absorption maxima are located around 400 nm. 

This result is not surprising since it was shown earlier that trichloromethyl ketones react more rapidly with methanol (alcohols) than with water under alkaline conditions.29 The ethanolic cleavage of a trichloromethyl ketone has been used to prepare ethyl 3,3-diethoxypropanoate,30 and aryl trifluoromethyl ketones can be cleaved to give carboxylic acids or esters.31 A similar reaction of 3-trifluoroacetylindole (19) with lithium dialkylamides affords good yields of the corresponding indole-3-carboxamides (20).3... 

The synthetic utility of the Haloform reaction is revealed further by a synthesis of isotopically pure (99.2%) CDCb by the reaction of trichloroacetophenone with NaOD in D20. The alkoxide-cleavage of trichloromethyl ketones has been employed to synthesize dihydropyridine esters (e.g., 24) in which ester exchange does not occur.59... 

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