I can think of the use of this in the reduction of phenylalanine to amphetamine, and reduction of tryptophan to AMT.
Journal of Organic Chemistry 66, 1672-1675 (2001)
Aliphatic carboxyl groups was efficiently reduced to the methyl group by triethylsilane in the presence of a catalytic amount (5 mol%) of the non-traditional lewis acid B(C6F5)3. To the best of our knowledge, this is the first example of exhaustive reduction of an aliphatic carboxyl function to a methyl group. Aliphatic aldehydes, acid chlorides and acid anhydrides also underwent complete reduction under similar reaction conditions.
All yields from all the published substrates range between 91 and 99%.
Experimental conditions:
Triethylsilane was added under an argon atmosphere to a mixture of the carboxylic acid (5 mmol) and B(C6F5)3 (5 mol%) in 5 ml DCM. The mixture was stirred at RT for 20h, the reaction quenched (Et3N, 0.25 ml), filtered through Celite and concentrated. THe residue was mixed with 40% HF (5-7 ml) in ethanol (30 ml) and refluxed for 7h. Water (60 ml) was added, the product extracted with 3x30ml pentane, The extracts washed with water, dried over MgSO4 and the solvent and Et3SiH was removed under vacuum. The residue was purified by flash column chromatography on silica gel to afford the products in 91-99% yield.
15 ml benzene, 15 ml acetone, 25 ml AcOH and 5 mmol(1,01 g) Mn(AcO)3 are boiled under N2 atmosphere until the color of the soln changes from dark brown Mn(AcO)3 to pink Mn(AcO)2 - approx. 1,5 h. The rxn mixtr is diluted w/40 ml ether, washed w/25 ml water and 2x25 ml 5% NaHCO3, the org layer is dried and evap'd to yield 40% phenylacetone(134 mg)
The effect of process parameters on the biotransformation of benzaldehyde to L-phenylacetylcarbinol (L-PAC) using a yeast isolate identified as Torulaspora delbrueckii was studied. The maximum yield of L-PAC obtained was (331 mg) per 100 ml biotransformation medium (glucose 3%, peptone 0.6% and at pH 4.5) from 600 mg of benzaldehyde with 8 h of reaction at 30+-2degreeC. Growing the organism in presence of 3% glucose reduced the biotransformation time to 120 min. Addition of 0.6% acetaldehyde (30-35%) lead to an increase in L-PAC yield to 450 mg%. Semi-continuous feeding of benzaldehyde (200 mg) and acetaldehyde (200 mul) four times at 30 min intervals could produce 683 mg of L-PAC/100 ml biotransformation medium. Chiral HPLC analysis of purified L-PAC and PAC-diol showed 99% enantiomeric purity. The cell mass was found to be reusable for biotransformation up to nine times when benzaldehyde and acetaldehyde levels were maintained at (350 mg and 350 mul)-(400 mg and 400 mul). At concentrations from 450 mg and 450 mul to 600 mg and 600 mul, however the cell mass could give efficient biotransformation only during one use.
Based on this you could get up to 100+ grams of L-PAC in a one day 5-gallon fermentation!!