Dialkyl cadmium reagents

The synthesis of 5-(2-oxoalky0resorcinols which are present in Cereale secale has been simply effected by the reaction of 3,5-dimethoxyphenylacetyl chloride with a dialkyl cadmium reagent in the folowing way (ref. 99). The 2-hydroxy compound shown as the final product is also present in the phenolic lipids of rye. 

These Fp-alkene complexes react with a variety of other nucleophiles,3 5 including water, alcohols, amines,3 6 phosphines, and thiols as well as carbon nucleophiles (enamines, organocuprates, enolates),3 2,3l8 and dialkyl cadmium reagents.3 9 Diene complexes such as 487 were converted to the corresponding cationic complexes (488), for example, and reaction with malonate gave 489. The iron complex was removed with trimethylamine N-oxide (Me N-O) to give 490.320... 

The reaction of quinolinium and isoquinolinium salts with dialkyl cadmium has been observed to be slow and occurs in relatively poor yield. The structures of the products are the same as those obtained from reactior with Grignard reagents and the yields ranged from 0-20% (40). Leadini references to other observed reactions of quinolinium and isoquinoliniuir salts with Grignard reagents can be found in the above cited review (31). 

One of the best known reactions of dialkyl cadmium compounds is that with acyl halides which results in the formation of ketones. The reactions of (CF3)2Cd glyme with CH, COBr and C6HhCOC1 were the third class of reactions of the trifluoromethylating reagent examined. However, the mixed trifluoromethylalkyl or -aryl ketones were not observed. The organic products obtained were the acyl fluorides (95% yield) along with difluorocarbene. The latter could be stereospecifically trapped at temperatures as low as -78°C. The addition of either lithium or magnesium halides to the reaction mixture did not affect the outcome (106). 

The acylation of organozinc reagents derived from dialkyl 1-bromo-1,1-difluoromethylphosphonates with acyl chlorides proceeds smoothly at room temperature to afford the desired products in moderate to good yields (60-77%, Scheme 3.75). Esters, lactones, and triflates did not react at all, even at Although these zinc and cadmium reagents appear to have similar reactivities,... 

The treatment of the cadmium reagent from a dialkyl (difluoroiodomethyl)phosphonate with SO2 affords the sulphinic acid derivatives (R0)2P(0)CF2S02H, isolated as their sodium salts . The product isolated from the reaction between diethyl (2-bromoethyl)-phosphonate and Na2S03 is believed to be (Et0)2P(0)CH2CH2S03Na, from which. 

Show the reagents neeessary to make 5-methyl-6-phenyl-4-oetanone using the dialkyl cadmium approach and then show how this ketone can be converted to 4,5-dimethyl-6-phenyl-4-octanol. 

In terms of their chemical behavior, dialkylzinc compounds generally react to transfer alkyl groups to other metals. Dialkyls of cadmium are usually prepared by the reaction of a Grignard reagent with a cadmium halide. 

Many dialkyl and diaryl cadmium compounds have found use as polymerization catalysts. For example, the diethyl compound catalyzes polymerization of vinyl chloride, vinyl acetate, and methyl methacrylate (45), and when mixed with TiCl can be used to produce polyethylene and crystalline polypropylene for filaments, textiles, glues, and coatings (45). With >50% TiCl diethyl cadmium polymerizes dienes. Diethyl cadmium maybe used as an intermediate ethylating agent in the production of tetraethyllead. The diaryl compounds such as diphenylcadmium [2674-04-6]> (C H Cd, (mp 174°C) are also polymerization catalysts. These compounds are also prepared using Grignard or arylUthium reagents in tetrahydrofiiran (THF) solvent but may be prepared by direct metal substitution reactions such as ... 

For most purposes the use of 1.0 mol of an alkyl or aryl bromide (for the preparation of the cadmium dialkyl or diaryl through the Grignard reagent) to 0.8 mol of the acid halide is recommended. This results in nearly equivalent molar ratios of the cadmium dialkyl and the acid halide, since the overall yield of the former is usually about 80 per cent. The entire preparation can be carried out in one flask without the isolation of intermediates. Experimental details are given for the preparation of l-chlorohexan-2-one (Expt 5.94). 

Dialkyl- and diaryl-cadmiums are best prepared by reaction of an anhydrous cadmium halide with the appropriate Grignard reagent or organolithium compound 154 perhalo compounds such as bis(pentafluorophenyl)cadmium can also be obtained in this way 155... 

Zinc, Cadmium, and Mercury.—Slurries of finely divided Cd or Zn, formed by codeposition of the appropriate metal vapour with a solvent, are active enough to form organometallic reagents (presumed to be metal dialkyls) by reaction with simple alkyl halides. Not only a-bromoesters, but also a-bromoketones, can be reacted with Zn to give Reformatsky-like reagents. Subsequent reaction with an... 

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