Showing papers in "The Alkaloids: Chemistry and Biology in 2018"

Benzoxazole Alkaloids: Occurrence, Chemistry, and Biology.

Abstract: Benzoxazole alkaloids exhibit a diverse array of structures and interesting biological activities. In spite of the extensive research done on the synthesis and biology, till date there is no concise update on this class of alkaloids. This chapter summarizes the literature on benzoxazole alkaloids till March 2017, which covers their isolation, characterization, possible biosynthetic origins, biological activities, and major synthetic approaches. These alkaloids have been broadly classified in the context of their sources, namely (i) fungal origin, (ii) marine origin, and (iii) plant origin.

Alkaloid Synthesis Using Organocatalysts.

Abstract: This chapter covers the literature since the advent, in the 21st century, of total syntheses of alkaloids using enantio- or diastereoselective organocatalytic reactions to construct the alkaloid scaffolds. The details of these alkaloid syntheses are described separately for each basic skeleton, including indole, indoline, oxindole, and piperidine alkaloids.

The Rigidins: Isolation, Bioactivity, and Total Synthesis—Novel Pyrrolo[2,3-d]Pyrimidine Analogues Using Multicomponent Reactions

Abstract: Rigidins (2–6) are pyrrolopyrimidine alkaloids isolated from marine tunicates. Since their isolation, refinement of their total syntheses, and biochemical evaluation, interest toward this pyrrolo[2,3-d]pyrimidine scaffold as a medicinal candidate has been triggered. The derivatization of these natural products has led to the discovery of a novel range of 7-deazahypoxanthines, which exhibit extremely potent anticancer activity in human cancer cell lines. A major breakthrough toward the synthesis of rigidin and various rigidin analogues has been the application of multicomponent reactions (MCRs). The rapid assembly of molecular diversity and flexibility displayed by MCRs makes it an attractive strategy for the preparation of rigidin-inspired small molecules. Furthermore, a number of rigidin-like 7-deazaxanthine compounds have been reported in the literature and the popularity of implementing MCRs to construct these 7-deazaxanthines is highlighted here. It is our hope that the synthetic methods described in this chapter will result in the further generation of rigidin-inspired compounds that will move on from being “hits” into “leads” in the medicinal chemistry drug discovery pipeline and potentially into anticancer therapeutics.

Moschamine-Related Indole Alkaloids.

Abstract: Moschamine-related alkaloids originate mainly from feruloylserotonin by cyclization or dimerization. This review provides a comprehensive overview on the achievements in the field of moschamine-related alkaloids. In the isolation part, a detailed structural characterization of moschamine-related alkaloids is followed by their spectral data. Besides the well-known antioxidative activities, other screened biological properties are also outlined. Since their isolation, different protocols have been developed to synthesize these alkaloids. The synthetic part is organized according to the different synthetic methodologies for the formation of key structural elements.