Convenient synthesis of (RS)-4-amino-3-hydroxybutyric acid

A new three-step synthesis of 4-amino-3-hydroxybutyric acid from an inexpensive starting material and under mild reaction conditions is described. Crotonic acid was brominated by the Wohl-Ziegler reaction to 4-bromocrotonic acid, which, in turn, was converted with ammonium hydroxide into 4-aminocrotonic acid. This compound, refluxed in water in the presence of a strong acid resin, afforded 4 amino-3-hydroxybutyric acid in good yields.

Cyclic Gaba-Gabob analogues I - Synthesis of new 4-hydroxy-2-pyrrolidinone derivatives

In the event that the GABA-GABOB system is involved in the initial phases of the learning and memory process, some new derivatives of 4-hydroxy-2-pyrrolidinone (I a) have been synthesized. The cyclic compounds of general formula (A) are more lipophilic than GABOB and should better enter brain fluids. The N-hydroxymethyl derivatives (II a...c) were prepared by addition of the suitable aldehydes to 4-acetoxy-2-pyrrolidinone (I b). In order to obtain the ethyl 4-hydroxy-2-oxo-1-pyrrolidineacetate (IV a) some synthetic routes starting from (I b), (III b) and from the 3-diazotetramic acid (V) were explored. However, the N-ethoxycarbonylmethyltetramic acid (X), obtained by Dieckmann cyclization of triester (VIII) and subsequent de-etho-xycarbonylation was reduced to (IV a). Ammonolysis of (IV a) afforded the acetamide (XI a). The O-acetyl derivatives (IV b) and (XI b) were also prepared.

Antimetabolites produced by microorganisms. XIII. The synthesis and microbiological production of a novel amino acid, L-2-amino-4-(2-aminoethoxy) butanoic acid

A novel amino acid, L-2-amino-4-(2-aminoethoxy-)-butanoic acid, was isolated from a fermentation broth of Streptomyces sp. X-11,085. It was shown to be identical with the chemical reduction product of an antimetabolite antibiotic, L-2-amino-4-(2-aminoethoxy)-trans-3-butenoic acid, a co-product in the fermentation. Addition of the title compound to the fermentation led to an enhanced yield of the antimetabolite suggesting that the saturated amino acid serves as a precursor for the antimetabolite.

Crystallization and solid-state reaction as a route to asymmetric synthesis from achiral starting materials

Many molecules which are achiral can crystallize in chiral (enantiomorphic) crystals and, under suitable conditions, crystals of only one chirality may be obtained. The formation of right- or left-handed crystals in excess is equally probable. Lattice-controlled (topochemical) photochemical or thermal solid-state reactions may then afford stable, optically active products. In the presence of the chiral products, achiral reactants may preferentially produce crystals of one chirality, leading to a feedback mechanism for the generation and amplification of optical activity. Amplification of optical activity can also be achieved by solid-state reactions. The optical synthesis of biologically relevant compounds by such routes may be envisaged.

Prebiotic synthesis of methionine

Methionine has been shown to be a product of the action of a spark discharge on a simulated primitive earth atmosphere containing CH(4), N(2), NH(3), H(2)O, and H(2)S or CH(3)SH. Acrolein has also been shown to be a product of the discharge and is proposed as an intermediate in the prebiotic synthesis of methionine and of glutamic acid, homocysteine, homoserine, and alpha,gamma-diaminobutyric acid.

Prebiotic synthesis of hydrophobic and protein amino acids

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, alpha-amino-n-butyric acid, alpha-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, alpha-hydroxy-gamma-aminobutyric acid, and alpha,gamma-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary alpha-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment.