The Reaction between α-Ketonic Acids and α-Amino Acids

Abstract

Two grams of retenediphenic anhydride was dry distilled, yellow vapors coming over accompanied by carbon dioxide. The distillate soon solidified to a yellow, crystalline material; yield, 1.5 g. (90%). From 95% ethanol it appeared as long, flat, sulfur-yellow prisms, m. p. 89-90°( corr.). Mixed with an equal amount of an authentic specimen of retene ketone of m. p. 88-89°( corr.), it melted at 89-90°( corr.).When retenediphenic acid or an intimate mixture of its anhydride and soda lime were distilled, retene ketone also resulted. In these cases, however, losses due to charring were appreciable and the yields lower. Summary 1.Dehydration of retenediphenic acid with 95% sulfuric acid yields two isomeric methylisopropylfluorenone carboxylic acids.2. These keto acids have been characterizedby their oximes, methyl esters and the oximes of the latter.3. Ammonia converts methyl acid retenediphenate into the previously reported retenediphenamic acid which undergoes the Hofmann degradation to yield 8-methyl-2-isopropylphenanthridone.Oxidation of the latter yields hemimellitic acid, thus establishing the structures of the compounds concerned.4. Treatment of methyl acid retenediphenate with 95% sulfuric acid at room temperature yields the methyl ester of l-methyl-7-isopropylfluorenone-5-carboxylic acid. The isomeric acid is therefore 6-methyl-2-isopropylfluorenone-5-carboxylic acid.5.

Reaction of glycine with glyoxylate: Competing transaminations, aldol reactions, and decarboxylations

“…A 12% yield of alanine was reported with optimum yields of products observed within a pH range of 1.9 to 2.6. The proposed mechanism is, for the most part, consistent with that suggested by Herbst and Rittenberg in that the transamination process does not involve an equilibrium between isomeric imine intermediates since no keto acid product was reported. Instead, it was suggested that the process involved a concerted decarboxylation and double bond migration; the cyclic transition state illustrated in Figure was proposed for this step…”

“…Specifically, α‐aminophenylacetic acid produced a near quantitative yield of benzaldehyde, alanine, and CO 2 upon reaction with pyruvic acid. A mechanism involving initial imine formation followed by double bond migration via a stepwise 2‐azaallylic proton transfer and subsequent decarboxylation was proposed . It was also reported that while the decarboxylation process proceeded under acidic conditions, it was inhibited under basic conditions.…”

Experiments on the metabolism of glycine

“…These compounds play an essential part in the metabolism of kidney and liver, and condensation of amino-acids with aldehydes and keto bodies is well known to take place purely chemically [Schiff, 1901;S0rensen, 1908]. More recently a similar simple condensation has been described by Herbst [1936] between amino-acids and pyruvic acid. Akasi [1937] reports tbe isolation of octopine, i.e.…”

The Transamination Reaction

“…The results of studies of the reaction between a number of keto acidamino acid combinations (35,38) are summarized in Table I. It should be pointed out that the reaction always led to the formation of racemic products.…”