Reactions with organocadmium compounds

P orniation of ketones. Reaction with organocadmium compounds. Discussed in Sec. 19.7. 

Though the first carbon atoms in LVII and LVIII are asymmetric, only one of the two possible stereoisomers was obtained in each case. It was suggested that the substantial quantities of sirup accompanying the production of these crystalline substances may have contained the other isomer. The authors propose a plausible ionic mechanism for the reaction of organocadmium compounds with tetraacetylglucosyl bromide, leading alternatively to compounds of types IV or LVII. It was reasoned that a carbonium ion was formed at carbon 1 by attack of the cadmium reagent at the bromide function ... 

Aliphatic ketones are readily prepared from the corresponding secondary alcohols, if these are available. More complicated aliphatic ketones can be prepared by the reaction of acid chlorides with organocadmium compounds. A... 

The success of the last reaction depends upon the inertness of the ester carbonyl groups towards the organocadmium compound with its aid and the use of various ester acid chlorides, a carbon chain can be built up to any reasonable length whilst retaining a reactive functional group (the ester group) at one end of the chain. Experimental details are given for l-chloro-2-hexanone and propiophenone. The complete reaction (formation of ketones or keto-esters) can be carried out in one flask without isolation of intermediates, so that the preparation is really equivalent to one step. 

Organocadmium compounds can be prepared from Grignard reagents or organo-lithium compounds by reaction with Cd(II) salts.180 They can also be prepared directly from alkyl, benzyl, and aryl halides by reaction with highly reactive cadmium metal generated by reduction of Cd(II) salts.181... 

The most common application of organocadmium compounds has been in the preparation of ketones by reaction with acyl chlorides. A major disadvantage of the use of organocadmium reagents is the toxicity and environmental problems associated with use of cadmium, and this has limited the recent use of organocadmium reagents. 

Organocadmium compounds can be prepared from Grignard reagents or organo-lithium compounds by reaction with Cd(II) salts.136 Organocadmium compounds can also... 

Many organocadmium compounds are known but few have been of commercial importance. Wanklyn first isolated diethyl cadmium in 1856. The properties of this and other dialkylcadmiums are listed in Table 4. In general, these materials are prepared by reaction of an anhydrous cadmium halide with a Grignard or alkyUithium reagent followed by distillation of the volatile material in an inert atmosphere or in vacuo. Only the liquid dimethyl compound is reasonably stable and then only when stored in a sealed tube. Dimethylcadmium is mildly pyrophoric in air and produces dense clouds of white, then brown, cadmium oxide smoke, which is highly toxic if breathed (45). When dropped into water, the liquid sinks in large droplets that decompose with a series of small explosive jerks and pops. For this reason, and particularly because of the low thermal stability, most dialkylcadmium materials are prepared and used in situ without separation, eg, in the conversion of acid chlorides to speciality ketones (qv) ... 

Grignard reagents derived from aryl bromides are readily prepared and may be converted into organocadmium compounds by treatment with cadmium chloride (cf. Section 5.8.4, p. 616). Reaction of an organocadmium with a carboxylic acid chloride constitutes a convenient synthesis of aryl alkyl ketones. 

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