I got a lot of questions here so let's approach them one at a time. First you ask WTF is FMOC-L-PHE, well that is the N-Flourenylmethoxycarbonyl carbamate of L-Phenylalanine [PHE] and BOC is the tert-Butoxcarbonyl-N carbamate analog of L-PHE. Being that we were discussing Phenylalanine, I thought we would know what the abbreviations meant and that we all knew what the commercially available blocked amino acids were. By the way, amino alcohols are also commercially available.
Amino acids are commercially available as the N Protected with FMOC, a base labile gruop, or with BOC, an acid labile group, depending upon your synthesis strategy and can be available by the ton for pharma synthesis. One such example would be PHE-methyl ester for aspartame production. I would strongly, no I would S-T-R-O-N-G-L-Y suggest using an N blocked ester with LAH because the reduction is smoother, does not Xpose LAH to a free acid [FOOM & KABOOM], plus the reduction of an N-Protected carbamate will yield an N-METHYL Amine... What a bonus! I have used LAH and it makes me nervous as hell due to its pyrophoric nature and large quantites can be explosive. That is why I recommend VITRIDE, a form of Sodium Aluminum Hydride that is reacted with two moles of Methoxyethanol and soluble in Toluene. It has 1/2 the reduction capabilities of LAH and can be easily handled in 5 gallon containers at 1 mole in 300 mL of liquid; it is also commercially available. It hydrolyses easily to form a paste and a Toluene layer that you pour off with your product in the solvent.
Finally I proposed a synthesis being half asleep at the time [ not tweaking here] about a starting material called L-DOPA aka 3,4-Dihydroxy-Phenylalanine. Search my other posts for a prep to N-BOC an amine, and the literature reference, to yield BOC-N-L-DOPA. Briefly, one would dissolve LDOPA in H2O to pH 10, 1 Molar, and add 1.1 Mole of Ditertbutyldicarbonate in MeCl2 with rapid stirring for 2-4 hr. Sep of MeCl2 and acidfy with citric acid to a pH of ~4 to yield the N-Protected carbamate. The Carbamate of 3,4 Dihydroxy can now be reacted with MeBr2 via one of Rhodiums preps to yield 3,4 Methylenedioxy-L-PHE. Again, I am proposing a synthesis that I have not actually done, but I have prepared tons of Blocked amino acids and alcohols for other purposes. Now reduce the above methylenedioxy compund with ZnBH4 to the alcohol. The ZnBH4 is here, UTFSE for a PDF on that little jewel to reduce amino acids to alcohols. With the reduction of the N-Blocked-L-DOPA Methylenedioxy compound, you should arrive with the N-Methylamino alcohol analog of 3,4-Methylenedioxy-L-Phenylalanol. I have done RDXN's on N-Blocked amino acid esters with Vitride and absolutely got 75+% yields of n-methyl amino alcohol, but not exactly with L-DOPA. Remember, when you toss a free organic acid on top of LAH or Vitride, or any other reducing agent, you lose Hydrogen right away as an acid-base RXN, so use the ester for a softer, more high yeild RXN. Who knows what kind of activity that 3,4 MD-L-PHE-ol might have as there is no literature reference to it. I cant get into more detail at this moment because I have to go, but I just wanted to save this thread by throwing in some chemistry ideas and save someones face from collecting flask parts.
PS: Just ask nicely, I'll be more than happy to elaborate.
