2-Acetamino- -ester

Benzo[b]thiophene-2-carboxylic acid, 3-acetamino-ethyl ester synthesis, 4, 875... 

Propansanre 376, 634 Magnesiumsalz 173 2-Acetamino- -iithylester 212 2-Acetamino-3-(3,4-dimethoxy-phenyl)- -athyl-ester 212... 

Es ist denkbar, daB die Bildung von 5-Methoxy-benzofurazan aus 2-Acetamino-5-methoxy-l-nitro-benzol und Carbamidsaure-ethylester mit Phosphor(V)-oxid in siedendem Xylol ebenfalls uber einc Carbamid-saure-ester-Zwischenstufe verliiufi48 ... 

Butensaure 3-(l-Carboxy-2-hydroxy-ethylamino)- -ethylester (K-Salz) XV/1, 345 Heptansaure 5-Methyl-7-nitro-4-oxo- -methylester E16d, 211 (Michael-Addition/Ringoffnung) Malonsaure Acetamino- -diethyl-ester IV/lc, 540 ( = NOH - ... 

Thiocarbamidsaure N,N-Dime-thyl- -S-(4-acetamino-phenyl-ester) E4. 303 (OR SR) Thiobarnstoif 3-Ethoxycarbonyl-... 

Butansaure 2-Acetamino-3-brom-3-chlor-2-methoxy- -tert.-butyl-ester E14a/2, 274 (Imin/R—OH)... 

Propansanre 2-Acetamino-3-(2-di-hydroxyboryl-phenyl)- -ethyl-ester XIII/3a, 633... 

Acid anhydrides in the presence of basic catalysts can be used instead of acyl chlorides in acylation reactions of thiols.Mixed anhydrides of N-protected amino acids and ethyl carbonate yield the corresponding S-f-butyl thiocarboxylic esters, which are useful reagents for peptide syntheses (equation 22). Acylation of thiols with ketenes (equation 23) is a method of long standing. In many cases the yields are nearly quantitative. Functionalities such as acetamino groups or carbon-carbon double bonds in the thiol are not attacked under the mild reaction conditions and optically active thiol esters are obtained without racemization. 3 ... 

Asymmetric hydrogenation. a-Hydroxy lactones and yacetamino-P-hydroxy esters in chiral form are created from a,y-diketo esters and 4-acetamino-3-keto-4-alkenoic esters, respectively, on hydrogenation. 

Acetaminosulfonyl-anilino)-4,5-di-etboxycarbonyl- 66 aus 2-Chlor-3-oxo-glularsaure-diethyl-ester/N-(4-Acetaminosulfonyl-phenyl)-thioharnstoflT 60 2-Acetamino-5-thiocyanat- 306 4-[2-Acetoxy-l-(acetoxy-methyl)-ethyl]-5-hydroxy- 190... 

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

Nitro.4-acetamino-beiU oe84uTe-methyl> ester 14, HO,... 

Butyxyl-gl3rcm 4 I 475. a-AcetaminO lMxjpionsftiiie-metii ester 4 II811. 

Prepared from phenoxyethyl bromide (559) and malonic ester by the procedure of Fischer and Blumenthal (293). o-Amino-y-butyrolactone hydrochloride has been prepared from y-butyrolactone through the o-bromo-y-butyrolactone lavak et cl. (521), by reduction of crroximino> y-but3rrolaotone with tin and HCl (450) or with Baney Nickel and hydrogen (450). The intermediate o-acetamino-y-butyrolactone was hydrolysed by the method of Hill and Robson (400). 

The relative ease with which acylamino acid esters are racemized appears to follow from the observations of Cherbuliez and Plattner (1929), who noted partial racemization when several acetamino acid esters were distilled at very reduced pressure. 

If amino acids are treated in hot acetic acid with one molecular equivalent of acetic anhydride, the corresponding acetamino acid is formed without appreciable racemization (Enoop and Blanco, 1925). However, if the proportion of acetic anhydride is increased to two equivalents, complete racemization results (Bergmann and Zervas, 1929). This loss of optical activity could also be produced by treating an active AT-acetyl- or JV-benzoylamino acid even with less than one equivalent of acetic anhydride at 100.° Amino acid esters were not racemized by this method. With peptides interesting differences were noted. Thus glycyl-L-leucine was readily racemized, but, with L-phenylalanyl-ii-tyrosine, examination of the two amino acids after hydrolysis indicated complete racemization of the tyrosyl residue and only partial loss of activity in the phenylalanine moiety. Isovaline, which does not possess a hydrogen atom in the o-position, was not affected under the conditions used. 

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