Reductive iodination

Reduction to Halocarbons. The best conditions for the reductive chlorination of ketones use the reagent combination Me2ClSiH/In(OH)3 (Eq. 241).331 Examples include conversions of aryl ketones to benzyl chlorides, ethynyl ketones to propargyl chlorides, and alkyl ketones to alkyl chlorides (Eq. 242).331 Addition of lithium iodide to the reaction mixture yields the corresponding iodide product. The combination of TMDO/I2 reductively iodinates aryl ketones and aldehydes in good yields (Eq. 243).357... 

Diiodosilane reduces acetals to alkyl iodides in a reductive iodination reaction (Eq. 312).358,505 Alkyl bromides are formed from the reductive bromination of benzaldehyde acetals with the combination Et3SiH/SnBr2.506... 

The reduction of epoxides occurs with the reagent combinations Et3SiH/BF3566 and EtjSiH/BI 3 01 T24<)7 The reductive iodination of epoxides is carried out with the combination of TMDO and iodine (Eq. 344).357 The yields are good to excellent. The reductive bromination of epoxides is accomplished in a similar manner. Trimethylchlorosilane is found to enhance these reactions.567... 

Reductive iodination of this vinylalane intermediate with IV-iodosuccinimide (NIS) yields the Z-trienyl iodide. Finally the free secondary alcohol is protected as TBS ether in a standard procedure to provide 8. 

ROH - RI,1 Reaction of I2 (1 equiv.) with BH3 QHsNfCjHsJj provides a diiodoborane amine complex in situ that converts alcohols into alkyl iodides in 62-86% yield. It also effects reductive iodination of carbonyl compounds. 

Alcohols are converted to alkyl iodides by reaction with A A-diethyl-aniline/borane/iodine. Reductive iodination is observed when this system reacts with ketones or with carboxylic acids934,935. Direct reduction of aromatic aldehydes to benzyl bromide is reported by Le Corre and coworkers, who have brominated benzaldehydes and acetophenones in presence of a trimethylamine/borane complex and have obtained benzyl bromides and a-bromoethylbenzenes, respectively936. See also Reference937. 

Diiodosilane (DIS) reagent for mild hydrolysis of ketals, acetals or reductive iodination of ketones and aldehydes (see 1st edition). 

A Oxygen evolution o DPC-supported DCIP reduction Iodination of D-1 protein... 

We have examined the applications of IBH2 and I2BH complexes for hydroboration of alkenes to obtain dialkyl and mono alkyl boranes. Unfortunately, these species disproportionate and hence the dialkyl and trialkyl boranes were not formed cleanly. Fortunately, however, the HBI2 and BI3 complexes are found to be useful for iodinations of alcohols, reductive iodinations of carbonyl compounds and hydroiodination of alkenes and alkynes. 

The aldehydes, ketones and carboxylic acids undergo reductive iodination under these conditions (Scheme 5) (J4),... 

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