Showing papers in "Mini-reviews in Organic Chemistry in 2016"

Cispentacin — enzymatic highlights of its 25-year history

Abstract: Because of its natural occurrence and novel biological activity, interest in the investigation of (1R,2S)-2-aminocyclopentanecarboxylic acid (cispentacin) has rapidly increased. Since its activity against Candida albicans, C. neoformans, and a systemic C. infection, a number of enzymatic strategies for its preparation in enantiomerically pure form have been developed. Structural optimization of cispentacin resulted in the synthesis of derivatives such as (1R,2S)-2-amino-4-methylenecyclopentanecarboxylic acid with even superior efficacy in view of antifungal activity. Not only cispentacin itself and some of its small-molecule derivatives have been described as molecules of interesting bioactivity but it was also found that the cyclopentane β-amino acid moiety may be a key element of larger molecules with important pharmacological properties, such as the antibiotic amipurimycin. The present review is intended to give a brief insight into the most relevant enzymatic strategies for the synthesis of 25-year-old cispentacin and its close analogues containing the cispentacin subunit. These methods are classified as indirect or direct strategies. Some practical details for the preparative-scale resolution of a selected racemate furnishing cispentacin with excellent ee and very good yield are highlighted at the end of this overview. © 2016 Bentham Science Publishers.

Triazaspirocycles: Occurrence, Synthesis, and Applications

Abstract: Natural products bearing a triazaspirocyclic motif have received significant attention in recent years. These compounds, which feature three nitrogen atoms attached to one quaternary carbon forming a spirocyclic scaffold, exhibit a wide range of biological activity and have promising applications in materials as well as in drug discovery. In this review article, we will discuss triazaspirocycles in Nature, their biological activity, and applications. Methods for the synthesis of triazaspirocycles as well as the reactivity of triazaspirocyclic scaffolds will be reviewed.

The application of molecular tethers in controlling axial chirality

Abstract: Atropisomeric biaryl compounds are an attractive target in organic chemistry due to their abundance in nature and their utility as ligands in catalysis. Among the methods available for their synthesis, the use of chiral tethers offers very high levels of stereocontrol. In this article, we review the application of molecular tethers in controlling axial chirality across a range of different ligands and natural products.