ABSTRACT
Covering: 2017-2019Guanidine natural products isolated from microorganisms, marine invertebrates and terrestrial plants, amphibians and spiders, represented by non-ribosomal peptides, guanidine-bearing polyketides, alkaloids, terpenoids and shikimic acid derived, are the subject of this review. The topics include the discovery of new metabolites, total synthesis of natural guanidine compounds, biological activity and mechanism-of-action, biosynthesis and ecological functions.
Subject(s)
Anura/metabolism , Bacteria/metabolism , Biological Products/chemistry , Fungi/metabolism , Guanidines/metabolism , Animals , Aquatic Organisms/chemistry , Aquatic Organisms/metabolism , Bacteria/chemistry , Bacteria/genetics , Biological Products/metabolism , Fungi/chemistry , Invertebrates/chemistry , Invertebrates/metabolism , Molecular Structure , Plants/chemistry , Plants/metabolism , Saxitoxin/chemistry , Saxitoxin/metabolism , Secondary Metabolism , Spiders/chemistry , Spiders/metabolism , Tetrodotoxin/chemistry , Tetrodotoxin/metabolismABSTRACT
A thermal protocol is reported for the formal insertion of nitric acid into aryldiazoacetates using Fe(NO3)3·9H2O. This strategy is mild and high yielding and allows the preparation of a large variety of members of an unprecedented family of organic nitrates. The nitrate group can be also readily transformed into other functional groups and heterocyclic moieties and can possibly allow new biological explorations of untapped potential associated with their NO-releasing ability.
ABSTRACT
In this work, using DFT calculations, we investigated the 1,4 and 1,5 asymmetric induction in boron enolate aldol reactions of α-alkoxy and α,ß-bisalkoxy methyl ketones. We evaluated the steric influence of alkyl substituents at the α position and the stereoelectronic influence of the oxygen protecting groups at the α and ß positions. Theoretical calculations revealed the origins of the 1,4 asymmetric induction in terms of the nature of the ß-substituent. The synergistic effect between the α,ß-syn and α,ß-anti-bisalkoxy stereocenters was elucidated. In the presence of the ß-alkoxy center, the reaction proceeds through the Goodman-Paton 1,5-stereoinduction model, experiencing a minor influence of the α-alkoxy center.