Bromotrichloromethane reagent

Dichloropropenoyl trimethylsilane, prepared by photochemically induced addition of bromotrichloromethane to the ethyl enol ether of acetyl trimethylsilane, undergoes completely regioselective addition-elimination upon treatment with lithium cyanocuprate reagents, giving the Z -3-chloroalk-2-enoyl silane products (vide supra, Section III.D.3)135. 

Amides. Barstow and Hruby have published two methods for synthesis of amides. In one, the two reagents are heated in THF to form the adduct the carboxylic acid and, after 10 minutes, the amine (2 equiv.) are added. The amide is obtained after a reflux period of about 1 hour. Yields are generally 80-90%. The second method involves triphenylphosphine, bromotrichloromethane, the acid, and the amine. The reported yields are somewhat higher than those obtained with the first method. One example of peptide synthesis by this method was reported (85% yield). 

Preparation. An aqueous solution of hypobromous acid prepared from siiver sulfite and bromine water is shaken with r-butanoi, and the product is extracted with trichlorofluoromethane (Freon 11) and distilled yield 42%. It is a reddish orange liquid with a bromine-like odor and is stable at 0° in the dark for long periods. It is rapidly destroyed at 85° or on irradiation, or by sodium bicarbonate. The reagent reacts with an alkane and bromotrichloromethane to form an alkyl bromide. 

Benzocyclopropene reacts with a variety of radical reagents (for example A -bromosuccinimide carbon tetrachloride bromotrichloromethane bromoform/benzoyl peroxide alkyl sulfide and ethane-1,2-dithiol with photolysis) to afford products derived from cleavage of the cyclopropane ring. The preferential mode of reaction consists of a chain reaction initiated by radical addition at Cl a followed by opening of the cyclopropyl radical to afford a benzyl radical. Yields are generally low except for the addition of the alkylsulfanyl radical, e.g. formation of 1, and no products derived from addition to the central tt-bond are formed. Cyclopropa[A]naphthalene reacts similarly with radicals and gives 2-methylnapthalene derivatives, while no addition to the central 7i-bond is observed. ... 

Transfer of a phenylseleno group can be accomplished simply by adding an excess (3 equiv) of diphenyl diselenide. Trichloroacetamide 7 was converted into bicyclic lactam 8 in 91% yield. On the other hand dimethylbromoacetamide 9 gave the corresponding Kharasch addition product 10 in 58% yield. The yield of 10 increased to 78% in the presence of 3 equiv of bromotrichloromethane, a bromine transfer reagent. 

DlchloromethyleDetris(diniethylamino)pho phorane, [(CH3)2N]3P—CCI2 (1). Mol. wt. 246.11. This reagent is prepared in situ from hexamethylphosphorous triamide and bromotrichloromethane. 

For in situ preparation, substitution of bromotrichloromethane for carbon tetrachloride (1, 223) results in more rapid formation of this Wittig reagent and also significantly improves the yields of 3,3-dichloroacrylonitriles formed by reaction with acyl nitriles. ... 

---