Aminocarboxylic acid chlorides

Chiral carboxyamides derived from acid chlorides and A-chiral cA-aminoindanol can be protonated and Li Cu transmetallated to generate copper enolates which react with A-lithium derivative of A-Boc-O-tosylhydroxylamine (LiBTOC) 31 to give a-A-Boc amino carboxamides in high yields and enantiomeric excess (Scheme 38) . The chiral auxiliary can be removed by acidic hydrolysis to obtain the a-aminocarboxylic acid. 

Other phosphorus compounds, e.g. PBrs, mixtures of PBrs and Br or PCI3/CI2 and phenyltetra-chlorophosphorane (PhPCU) have been used to convert amides to imidoyl halides. The formation of imidoyl halides proceeds under mild conditions by action of triphenylphosphine/CCU or triphenylphos-phine dihalides on secondary amides or ketoximes. The work-up procedure can be facilitated by use of polymer-supported triphenylphosphine/CCU. By the action of POCI3, phenyl- or methyl-phos-phonic acid dichloride on aminocarboxylic acid thiol esters in the presence of triethylamine the imidoyl chlorides (205 equation 114) are formed in moderate to good yields. The mechanism of this reaction has not been established. The methylene dialkylchlorophosphorane (206 equation 115) allows the conversion of secondary aromatic amides to imidoyl chlorides under very mild conditions. ... 

Aminocarboxylic acid esters undergo reaction with hydroxamoyl chloride in a similar fashion to yield the substitution products XXIV however, saponification of the ester group occurs, unless carboxyethyl-hydroxamoyl chloride is being used ( ),... 

Stannous chloride a-Aminocarboxylic acids from hydrocarbons... 

Thionyl chloride acetic anhydride Protection of a-aminocarboxylic acid groups as 5-oxazolidones... 

Hydrogen chloride Aminocarboxylic acids from lactams... 

Phosgene/hydrogen chloride Isocyanatocarboxylic acid chlorides from aminocarboxylic acids... 

Polycondensation is easier with amino carboxylic esters, since the —COOR-group is less resonance-stabilized (cf. nylon 7 and nylon 11). Even less stable, and therefore very reactive, is the acyl chloride group. However, the acyl chloride of the a,o)-aminocarboxylic acids is not easy to handle (purify, etc.), and it is not easy to control polymer formation. 

Startg. 2,3-azetidinedione added to ca. 1.4 eqs. m-chloroperoxybenzoic acid in methylene chloride at — 20°, the mixture stirred for 60 min, treated dropwise with a soln. of / r/-butylamine and pyridine in the same solvent, and stirred at room temp, for 70 min product. Y 70%. F.e. and a-aminocarboxylic acid esters with alcohols, also 3-(a-nitroalkylidene)-2-azetidinones, s. F.P. Cossio et al., Tetrahedron Letters 29, 3133-6 (1988). 

Phosphorus oxide chloride Regiospecific prepn. of azomethinium salts from (x-rerf-aminocarboxylic acids N-Condensed heterocyclics via cyclic azomethinium salts... 

The phosgenation of isatoic anhydride and aminocarboxylic and amino-sulfonic acids, to afford isocyanatoarylcarbonyl chlorides and isocyanato-arlsylfonyl chlorides, is also catalyzed by iminium chlorides. 

Zinc chloride s. under R SiH Lithium tetrahydridoborate a-Hydroxymethyl-a-aminocarboxylic aeids from a-acetamino-a-cyanocarboxylic acid esters... 

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