synthesis of 2-bromo-4-methylpentane from 4-methylpentan-2-ol

I think OP is looking to prep this molecule and wants a synthesis. His prof gave him a bare minimum piece of advice and now hes chasing that (I think) inferior pathway due to its 2 step nature and having to get tosic acid out. I personally avoid DMF/DMSO as much as possible. If OP wants to use the NaBr route, may I suggest using methanol instead of DMF as a solvent, its easier to remove.

For using PBr3, its so commonplace I frankly had trouble finding a source that didn't just say "We used PBr3 and pyridine in some organic solvent, youre a chemist, we arent gonna spell this out." I'm surprised it wasn't the first thing brought up here, its in virtually any academic stockroom.

Google scholar with "PBr3 pyridine" (https://scholar.google.com/scholar?start=0&q=pbr3+pyridine&hl=en&as_sdt=0,11) gives hundreds of variations on the same thing. Feel free to hunt through supporting info to find one that spells it out. Or scifinder probably can lead you to one.

Basically, take a few equivalents of PBr3 and pyridine and add it to some anhydrous aprotic solvent like DCM in an ice bath. Take out of ice bath after addition and stir it for a few hours/overnight, then extract it with 1M HCl, then water. Rotovap organic layer solvent. Youre done. If theres still pyridine in it (a gentle sniff will tell you) use aqueous CuSO4 extraction to get it all off.

If using PBr3, would that not make the mixture very acidic, risk for rearangement?

I would expect that the substitution will be slower in methanol as the solvent than DMF or DMSO.

The third edition of Jerry March's book give some information in 0-67 on page 382.  Both reactions discussed were performed in HMPT and neither one underwent a rearrangement.  One of the references is Stork, Grieco, and Gregson, Tet. Letters, 1393 (1969).  A number of papers are cited in footnote 226, which deals with the substitution of neopentyl tosylates by halides in HMPT or DMSO as solvents.  For example, Paquette and Phillips, Tetrahedron Letters, 4645, 1967.  Section 0-68 also has some pertinent information, such as on PBr₃.  The alkyl tosylate method is also mentioned in footnote 795.

Uh...guys. PBr3. one step

Maby not, the phosphorus acid formed is not so strong acid.

Is the bromide the final product you need to make, or are you eliminating/substituting it after? In which case you could just make the tosylate (or equivalent) and displace that, avoiding the bromide altogether.

Both are well known reactions - your exact substrate may not be in the literature but similar are.

See e.g. http://cssp.chemspider.com/article.aspx?id=155 for the first step

Triphenylphosphine, carbontetrabromide would do the trick, saving one step.

True enough, though tosylation and bromination has been already given as conditions, we're just after a procedure - not alternative reagents etc.

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Uh...guys. PBr3. one step

Do you have a primary reference for this with experimental (which I think is what N30NB14CK is actually after)