Neopentyl halides reduction

When 2,2-dimethylhexyl-l-iodide (10), a saturated neopentyl-type halide, was treated with LiAlH4 in THF-d8, the corresponding reduction products (11a) and (lib) were obtained quantitatively, and 95% of the reduction product contains di, as shown in eq. 9.5 [14]. This result again indicates a 2,2,-dimethylhexyl radical is the real intermediate for the reduction product. 

Not only radical scavengers, radical reduction and/or radical dimerization products but also radical probes were used in order to prove the presence of radicals as intermediates along the S l propagation cycle. Thus the formation of cyclized and uncyclized substitution products was taken as an indication of radical intermediates in the reaction of neopentyl-type halides containing a cyclizable probe of the 5-hexenyl type 2. These reactions were performed with PhS and Ph2P ions as nucleophiles (equation 13)52. 

Reduction of aikyl halides. Allylic and benzylic chlorides and bromides are reduced by the reagent almost instantaneously at 25° (S 2 displacement). Simple primary halides are completely reduced in 2 min. Even neopentyl bromide is reduced to neopentane (96% yield) in 3 hr. under reflux. Secondary cycloalkyl bromides are reduced at 25° in 24 hr. Even CAro-2-bromonorbomane (I) can be reduced quantitatively. The... 

Representative reductions of alkyl halides with LiBEtyH are shown in Table 4. Most alkyl halides, including chlorides, are reduced under mild conditions in essentially quantitative yields. Even hindered alkyl halides, such as neopentyl bromide and cAro-norbomyl bromide, undergo facile reduction to the corresponding alkanes in more than 96% yield with this reagent. 

---