The first total synthesis of chondrochloren A is accomplished using a 1,2-metallate rearrangement addition as an alternative for the Nozaki-Hiyama-Kishi reaction. This transformation also avoids the inherent challenges of this polyketide segment and provides a new, unprecedented strategy to assemble polyketidal frameworks. The formation of the Zenamide is accomplished using a Z-selective cross coupling of the corresponding amide to a Z-vinyl bromide.
A sequence of seven reactions (stereocontrolled allylation, Mitsunobu reaction, ring closing metathesis, and amino/amido intramolecular nucleophilic addition) efficiently convert the inexpensive starting 2‐piperidine ethanol into a small library of enatiomerically pure nitrogen containing compounds characterized by three new scaffolds that present a relevant diversity. This simple approach encroaches the further exploration of the chemical space.
Aza-alkylation reaction at indole C3 position allows the introduction of a differently substituted aminomethyl group, with the formation of a new stereogenic centre. The reaction involves essentially three different partners:...
Four different hybrid compounds have been efficiently synthesized by conjugation of deacetylthiocolchicine with pironetin‐inspired derivatives. The modest bioactivity and the apparent absence of interaction with α‐tubulin is explained by a posteriori in silico investigation, which suggests a relevant distance between the thiocolchicine binding site and the proper pocket on the α‐tubulin. The modest activity on resistant cells suggested that the lipophilic nature of the linker used renders the resulting compounds better substrates for p‐Gp efflux pumps. The study better clarifies the design of bivalent compounds that target hetero tubulin/microtubules.
The piperidine ring is a widespread motif in several natural bioactive alkaloids of both vegetal and marine origin. In the last years, a diversity-oriented synthetic (DOS) approach, aimed at the generation of a library of piperidine-based derivatives, was developed in our research group, employing commercially available 2-piperidine ethanol as a versatile precursor. Here, we report the exploration of another ramification of our DOS approach, that led us to the stereoselective total synthesis of (–)-anaferine, a bis-piperidine alkaloid present in Withania somnifera extract. This natural product was obtained in 9% overall yield over 13 steps, starting from a key homoallylic alcohol previously synthesised in our laboratory. Therefore, the collection of piperidine-derivatives accessible from 2-piperidine ethanol was enriched with a new, diverse scaffold.
The design of artificial enzymes has emerged as a promising tool for the generation of potent biocatalysts able to promote new-to-nature reactions with improved catalytic performances, providing a powerful platform for wide-ranging applications and a better understanding of protein functions and structures. The selection of an appropriate protein scaffold plays a key role in the design process. This review aims to give a general overview of the most common protein scaffolds that can be exploited for the generation of artificial enzymes. Several examples are discussed and categorized according to the strategy used for the design of the artificial biocatalyst, namely the functionalization of natural enzymes, the creation of a new catalytic site in a protein scaffold bearing a wide hydrophobic pocket and de novo protein design. The review is concluded by a comparison of these different methods and by our perspective on the topic.
The Front Cover shows a playful representation of the fascination to explore, that always moved science forward. In particular, the exploration of the Chemical Space is a challenging experience that excites creativity and enthusiasm of the organic chemists. The 2‐piperidine ethanol appears as a kite in the hands of a bold researcher to give vent to the imagination, looking for new structures and landing on known chemical entities. More information can be found in the Full Paper by D. Passarella et al.
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