Anisotropic NMR has gained increasing popularity to determine the structure and specifically the configuration of small flexible, non‐crystallizable molecules. However, it suffers from the necessity to dissolve the analyte in special media such as liquid crystals or polymer gels. Generally, small degrees of alignment are also caused by an anisotropic magnetic susceptibility of the molecule, for example induced by aromatic moieties. For this mechanism the alignment can be predicted via DFT. Here we...
Mon May 04, 2020 18:24
A copper‐based complex that contains a sulfonate N‐heterocyclic carbene ligand was first reported 15 years ago. Since then, these organometallic entities have proven to be uniquely effective in catalyzing an assortment of enantioselective transformations, including allylic substitutions, conjugate additions, proto‐boryl additions to alkenes, boryl and silyl substitutions, hydride–allyl additions to alkenyl boronates, and additions of boron‐containing allyl moieties to N‐H ketimines. In this review...
Mon May 04, 2020 17:55
The collective synthesis of glycosylated monoterpenoid indole alkaloids is reported. A highly diastereoselective Pictet–Spengler reaction with α ‐cyanotryptamine and secologanin tetraacetate as substrates, followed by a reductive decyanation reaction, was developed for the synthesis of (–)‐strictosidine, which is an important intermediate in biosynthesis. This two‐step protocol in a flask was established as an alternative to the biosynthetically employed strictosidine synthase. Furthermore, after...
Mon May 04, 2020 16:27
Alkyne is a biologically significant moiety found in many natural products and a versatile functional group widely used in modern chemistry. Recent studies have revealed the biosynthesis of acetylenic bonds in fatty acids and amino acids. However, the molecular basis for the alkynyl moiety in acetylenic prenyl chains occurring in a number of meroterpenoids remains obscure. Here, we identify the biosynthetic gene cluster and characterize the biosynthetic pathway of an acetylenic meroterpenoid biscognienyne...
Mon May 04, 2020 14:54
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