An otc way to PPA, what I,ve dug up so far
Synthesis of aminoalcohols by aldol condesation of aminoacids with aromatic aldehydes.
The alanine is reduced via -COOH => -CH2-OH
Reaction between aromatic aldehydes and a-amino acids. I. New facts on the Akabori reaction. Takagi, Eiichi. J. Pharm. Soc. Japan (1951), 71 648-51. Journal written in Unavailable.
Abstract
The Akabori reaction (I) (C.A. 41, 3774g) on BzH and dl-MeCH(NHMe)CO2H (II) with and without pyridine and removal of the unreacted BzH by steam distn. gave dl-ephedrine and dl-y-ephedrine. Similarly, direct heating of piperonal and II gave 2 dl-1-(3,4-methylenedioxyphenyl)-2-methylamino-1-propanols. A new reaction (III), differing from I, takes place on heating BzH and DL-alanine directly; PhCH2NH2, PhCH(OH)CHPhNH2 (2 dl-compds.), AcH, and CO2 are formed. It is considered that the I-type reaction occurs when the N of the amino acid is secondary and the III-type reaction when it is primary.
Fester5 sites that direct heating of 20g N-methyl-alanine
with 50g Bnz at 150deg untill fizzing stops, produces
12g of a mixture 3g ephedrine and 9g pseudoephedrine isomers.
Reactant BRN 471223 benzaldehyde
1720250 DL-alanine
Product BRN 3196917 (1RS,2RS)-2-amino-1-phenyl-propan-1-ol
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Reaction Details
Reaction Classification Preparation
Temperature 140 øC
Other conditions Erwaermen des Reaktionsprodukts mit wss.-aethanol. HCl
Ref. 1 2262852; Journal; Takagi et al.; YKKZAJ; Yakugaku Zasshi; 73; 1953; 1086; Chem.Abstr.; 1954; 12021;
As promised, here are some more refs on the interesting condensation reaction between aromatic aldehydes and glycine/alanine:
BER 25: 3445 (1892) + 52 :1734 ('19)
ANN. 284: 36 + 307: 84
JCS 1943 ('26) + 2600 ('22)
JACS 76: 1322 ('54)
J.PHARM.SOC.JAP. 67: 218 ('47)
Most of the articles are pretty old to say the least but they contain some interesting stuff on the reaction we're interested in here. I'm especially interested in the J.Pharm.Soc.Jap article, which describes the preparation of a methylenedioxy-substituted phenylserine. But the practical way to go is definitely as mentioned in a certain patent, that is using a two-phase solvent system. This prevents the benzylidene phenylserine from crystallising and makes sure that the reaction mixture can be stirred at all times.
After decarboxylation, these phenylserine derivates turn into amino alcohols, the perfect substrates for aminoxazolines. By substituting the benzaldehyde, a lot of phenylserine and amino alcohol derivates can be made and thus a lotta aminoxazolines!
So with some 10x experiments with 20g alanine + 50g BnZ
a massive 15% return sux, any suggestions besides learn how to make nitroethane?