zephler1 - 8-10-2014 at 04:46
Some references suggest at best, one can expect a 65% yield (using 5 equivalents of LiAlH4); does anyone have any real world experience with yields
from this reaction?
There is a document on Rhodium "Large scale MDA from piperonal" in which the authors use just a 2x excess of LiAlH4, explicitly state that they do not
reflux the mixture being reduced and that they get a 77% yield. This statement is highly suspect as not one published paper comes close to that
yield, and bear mind that these papers all use a 5x stoichiometreic ratio of LiAlH4 and they reflux - I have a hard time believing that the key to
higher yields and better atom economy is the lack of refluxing - any comments?
Templar - 8-10-2014 at 18:35
oops, this looks a bit too obviously drug related to be on here!
LAH reductions are not very fun. LAH is dangerous blah blah flammable ethers blah blah
Just run it with Al/Hg and see what you get. Workups can get complex quickly with LAH. I have reduced novel phenyl propyl nitroalkenes using aluminum
turnings in good consistent yield of roughly 50%, just run with that.
If you're dealing with nitrostyrenes, its best to use Zn/acid reduction, borohydride and then Zn reduction, or borohydride then Pd/C CTH reduction.
LAH if you have plenty of it and THF to use as the solvent because ether SUCKS