A stereoselective synthesis of (2S,4R)-δ-hydroxyleucine methyl ester: a component of cyclomarin A

Recent Advances in the Hydroxylation of Amino Acids and Its Derivatives

Hydroxy amino acids (HAAs) are of unique value in the chemical and pharmaceutical industry with antiviral, antifungal, antibacterial, and anticancer properties. At present, the hydroxylated amino acids most studied are tryptophan, lysine, aspartic acid, leucine, proline, etc., and some of their derivatives. The hydroxylation of amino acids is inextricably linked to the catalysis of various biological enzymes, such as tryptophan hydroxylase, L-pipecolic acid trans-4-hydroxylase, lysine hydroxylase, etc. Hydroxylase conspicuously increases the variety of amino acid derivatives. For the manufacture of HAAs, the high regioselectivity biocatalytic synthesis approach is favored over chemical synthesis. Nowadays, the widely used method is to transcribe the hydroxylation pathway of various amino acids, including various catalytic enzymes, into Corynebacterium glutamicum or Escherichia coli for heterologous expression and then produce hydroxyamino acids. In this paper, we systematically reviewed the biosynthetic hydroxylation of aliphatic, heterocyclic, and aromatic amino acids and introduced the basic research and application of HAAs.

Synthesis of the Sex Pheromone of the Tea Tussock Moth Based on a Resource Chemistry Strategy

Synthesis of the sex pheromone of the tea tussock moth in 33% overall yield over 10 steps was achieved. Moreover, the chiral pool concept was applied in the asymmetric synthesis. The synthesis used a chemical available on a large-scale from recycling of wastewater from the steroid industry. The carbon skeleton was constructed using the C4+C5+C8 strategy. Based on this strategy, the original chiral center was totally retained.

Synthesis of side-chain oxysterols and their enantiomers through cross-metathesis reactions of Δ22 steroids

A synthetic route that utilizes a cross-metathesis reaction with Δ²² steroids has been developed to prepare sterols with varying C-27 side-chains. Natural sterols containing hydroxyl groups at the 25 and (25R)-26 positions were prepared. Enantiomers of cholesterol and (3β,25R)-26-hydroxycholesterol (27-hydroxycholesterol) trideuterated at C-19 were prepared for future biological studies.

Applications of oxazolidinones as chiral auxiliaries in the asymmetric alkylation reaction applied to total synthesis

In this review, a number of applications of chiral oxazolidinones in the asymmetric alkylation reaction applied to total synthesis are described.

Synthesis of fully protected, reverse N-prenylated (2S,3R)-3-hydroxytryptophan, a unique building block of the cyclomarins

The rather exotic amino acid of the cyclomarins, is obtained in enantio- and diastereomerically pure and fully protected form.

Directed studies towards the total synthesis of (+)-13-deoxytedanolide: simple and convenient synthesis of the C8-C16 fragment

A straightforward synthesis of the enantioenriched C8-C16 south part of (+)-13-deoxytedanolide has been reported. The strength of this approach relies on the preparation of similar functionalized fragments via the transformation of a unique dihydrofuran building block through a 1,2-metallate rearrangement.

Macrolides and alcohols as scent gland constituents of the Madagascan frog Mantidactylus femoralis and their intraspecific diversity

Acoustic and, to a lesser degree, visual signals are the predominant means of signaling in frogs. Nevertheless, certain lineages such as the mantelline frogs from Madagascar use the chemical communication channel as well. Males possess femoral glands on the hind legs, which recently have been shown to contain volatile compounds used in communication as pheromones. Many mantelline species occur in sympatry, and so far species recognition is regarded to occur mainly by acoustic signals. The analysis of the gland constituents of Mantidactylus femoralis by GC/MS revealed the presence of volatile macrolides and secondary alcohols. The new natural products mantidactolides A (4) and B (6), as well as several methyl carbinols, were identified, and their structures were confirmed by synthesis. The analysis of individuals from different locations of Madagascar revealed the presence of two groups characterized by specific patterns of compounds. While one group contained the alcohols and mantidactolide B, the other showed specific presence of the macrolides phoracantholide I (1) and mantidactolide A (4). Genetic analysis of some individuals showed no congruence between genetic relatedness and gland constituents. Several other individuals from related species had different gland compositions. This suggests that a basic set of biosynthetic machinery might be available to a broader group of related species.