Methyl trichloroacetate

In an autoclave, methyl trichloroacetate had been mixed with trimethyiamine. The medium was not cooled. A violent reaction caused a sudden pressure rise, which reached 400 bar. It was thought that an intramolecular dehydro-halogenation of chloroester had formed the unstable lactone according to the equation below. Its decomposition was responsible for the incident ... 

Allenylcobaloximes, e.g. 26, react with bromotrichloromethane, carbon tetrachloride, trichloroacetonitrile, methyl trichloroacetate and bromoform to afford functionalized terminal alkynes in synthetically useful yields (Scheme 11.10). The nature of the products formed in this transformation points to a y-specific attack of polyhaloethyl radicals to the allenyl group, with either a concerted or a stepwise formation of coba-loxime(II) 27 and the substituted alkyne [62, 63]. Cobalt(II) radical 27 abstracts a bromine atom (from BrCCl3) or a chlorine atom (e.g. from C13CCN), which leads to a regeneration of the chain-carrying radical. It is worth mentioning that the reverse reaction, i.e. the addition of alkyl radicals to stannylmethyl-substituted alkynes, has been applied in the synthesis of, e.g., allenyl-substituted thymidine derivatives [64],... 

Hexachloroacetone is fluorinated87 over potassium tetrafluorocobaltate(III) at 230°C. As with nonchlorinated ketones (Section 25.1.1.3.), no ketonic products are detected, and low yields of trichlorofluoromethane, methyl dichlorofluoroacetate (the reaction mixture is worked up by methanol treatment) and methyl trichloroacetate are isolated. 

The addition of methyl trichloroacetate to 20 is initiated by benzoyl peroxide or Fe(CO)s (equation 113). In the latter case, conducting the nucleophile-assisted reaction in an aprotic solvent (HMPA or MeCN) results in a higher yield of the adduct337. 

Other polyhalogenated compounds can be used with similar success. CpFe(CO)2 dimer leads to the formation of mixtures of lactones and esters when reacted with an alkene and methyl trichloroacetate [79] with the lactone being the major product (Scheme 3.10). Similar results were reported earlier by Freidlina and Velichko [80]. FeCl3 and Fe(CO)5 are both suitable for catalyzing the addition of methyl dibromoace-tate to electron-deficient alkenes such as methyl propenoate. It was observed that the ratio of products (acyclic vs. lactone) could be tuned by varying the reaction conditions. In all cases, the acyclic product is predominantly formed. Only in the presence of a co-catalyst such as N,N-dimethylaniline are small amounts of lactone observed. Noteworthy, elevated temperatures (above 100 °C) are necessary for this transformation. 

Methyl formate Methyl acetate Methyl propionate Methyl isobutyrate Methyl difluoroacetate Methyl trifluoroacetate Methyl monochloroacetate Methyl dichloroacetate Ethyl trichloroacetate Methyl trichloroacetate Methyl cyanoacetate Methyl methoxyacetate Methyl benzoate... 

Analogous carbonyl-forming eliminations occur with the adducts formed between organotin oxides or alkoxides and trihalogenomethyl aldehydes or ketones, and tributyl-trichloromethyltin was first prepared by the elimination of methyl trichloroacetate from the adduct of tributyltin methoxide and hexachloroacetone.135 136... 

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