DCME reaction

The reduction-hydroboration of alkyldihalogenoboranes provides a more general approach to unsymmetrical dialkylboranes. The reduction of RBX2 (X = Br, Cl) with LiAlH followed by the addition of a terminal olefin gives RR BX. Redistribution does not occur, as proved by clean conversion of these dialkylhalogenoboranes into ketones via DCME reaction. However, if the olefin is present in the reaction mixture prior to the reduction, redistributed products are formed ... 

The oxidation affords terminal diols and 1,5-diols. The DCME reaction affords the mixture of ketones in each case, and only the isomerized, major ketone 2-alkylcyclohexanone is isolated, identified, and determined for percentage yield (Scheme 32.5) [13]. 

Single-Carbon Insertion Reactions. Carbonylation, cyanidation, and "DCME," and related reactions are convenient general processes developed to bring about the transfer of organic groups from boron to a siagle-carbon atom. 

The preparation of a functional segmented block copolymer was also investigated (scheme ll).15 First hydroboration polymerization of the oligomer using thexylborane was carried out. Then the obtained organoboron polymer was subjected to a chain-transformation reaction (DCME rearrangement). DCME and lithium alkoxide of 3-ethyl-3-pentanol in hexane was added to a THF solution of the polymer at 0°C. 

The reaction of 24.and HC1 yields alkylchloroborane triphenyl phosphane complexes 28, which can be converted with olefins in the presence of benzyliodide 25 (15). The dialkylchloroboranes 32 thus formed can be transformed into ketones 33, with sodium methylate and then the DCME-technique of H.C. Brown (16). 

---