Synthesis a-aminocarboxylic acid

The beneficial effect of surfactants on enantioselective hydrogenations in water was exploited in the synthesis of a-aminophosphinic and a-aminophosphonic acids. These compounds are stmctural analogues of a-aminocarboxylic acids and their peptides find use as herbicides, bactericides and antibiotics [150,151]. With [Rh(BPPM)(COD)]Bp4 and similar catalysts fast ractions and e.e.-s up to 98% could be obtained in water in the presence of SDS (Scheme 3.12). 

The degradation of a-aminocarboxylic acids has proven to be a useful method for the preparation of iminium salts. For example, treatment of N- methylpipecolic acid (97) with phosphorus oxychloride gave 94% of the iminium salt (98) (Scheme 7) (76JA7448). The synthetic utility of this approach is illustrated by the synthesis of tetrahydroberberine (Scheme 8) (78JOC2115). The advantage of this method for the preparation of iminium salts is that the position of the carbon-nitrogen double bond can be controlled. 

The reaction product obtained from diphenylcarbodiimide and hydrogen cyanide is an intermediate in Sandmeyers indigo synthesis. HCN can also be eliminated from a-aminocarboxylic acid nitriles 589 to give l-cyano-N,N -disubstituted formamidines 590 and imines 591. ... 

Decarboxylative acetoxylation and methoxylation of a-aminocarboxylic acids proceed smoothly, yielding synthetically useful intermediates. For example, the versatile intermediate (LX) for the synthesis of thienamycine is prepared by electrodecarboxylative acetoxylation of 4-carboxy-2-azetidinone (LIX) in an AcOH-MeCN-AcONa-(Pt) system [134] ... 

Naskar, D., Roy, A., Seibel, W. L., Portlock, D. E. Hydroxylamines and sulfinamide as amine components in the Petasis boronic acid-Mannich reaction synthesis of N-hydroxy or alkoxy-a-aminocarboxylic acids and N-(tert-butyl sulfinyl)-a-amino carboxylic acids. 

Sodium bis(trimethylsilyl)amide a-Aminocarboxylic acid esters from halides Synthesis with addition of 2 C-atoms... 

N-Protected a-aminocarboxylic acid amides. A soln. of N-(4-methoxybenzyloxycar-bonyl)alanine in 4 1 dichloromethane/dimethylformamide treated with 1-hydroxy-benzotriazole and dicyclohexylcarbodiimide, stirred for 30 min, 25% aq. NH3 added, and stirred for 3-5 h until reaction complete (t.l.c.) - N-(4-methoxybenzyloxycar-bonyl)alanine amide. Y 83%. The method is high-yielding and racemization-free. F.e. inch Boc- and Cbz-aminoacid and dipeptide derivs. s. S.-T. Chen et al.. Synthesis 1989, 37-8 with 2-ethoxy-N-ethoxycarbonyl-l,2-dihydroquinoline and NH4HCO3 cf. S. Nozaki, I. Muramatsu, Bull. Chem. Soc. Japan 61, 2647-8 (1988). 

Synthesis of a-aminocarboxylic acids from bromides Br - C(NHAc)(COOR)2 via acetylaminomalonic acid esters cf. 22, 837 via formamidomalonates with NaOEt/ EtOH as base, polyfluoroalkoxy- and polyfluoroalkylthio-phenylalanine derivs., s. M.T. Kolycheva et al., Zh. Org. Khim. 25, 1306-11 (1989). 

Di(isopinocampheyl)boranelacetone cyanohydrin a-Aminocarboxylic acids from nitriles Asym. synthesis with addition of 1 C-atom... 

Asym. synthesis of a-aminocarboxylic acids via tetrahydro-l,4-oxazin-2-ones... 

Dry methyl methylthiomethyl sulfoxide allowed to react at room temp, with NaH in tetrahydrofuran, benzonitrile added, and stirred 16 hrs. at 50 l-methylsulfinyl-l-methylthio-2-amino-2-phenylethylene. Y 75%. - This is the first step of a method for the synthesis of a-aminocarboxylic acid derivs. from nitriles with addition of 1 C-atom. F. e. s. K. Ogura and G. Tsudiihashi, Am. Soc. 96,1960 (1974). 

N-Subst. a-aminocarboxylic acids by Mannich synthesis with glyoxylic acid... 

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