The first and enantioselective total synthesis of (+)-plumisclerin A, a novel unique complex cytotoxic marine diterpenoid, has been accomplished. Around the central cyclopentane anchorage, a sequential ring-formation protocol was adopted to generate the characteristic tricycle[4.3.1.0 ]decane and trans-fused dihyrdopyran moiety. Scalable enantioselective La -catalyzed Michael reaction, palladium(0)-catalyzed carbonylation and SmI -mediated radical conjugate addition were successfully applied in the synthesis, affording multiple grams of the complex and rigid B/C/D-ring system having six continuous stereogenic centers and two all-carbon quaternary centers. The trans-fused dihyrdopyran moiety with an exo side-chain was furnished in final stage through sequential redox transformations from a lactone precursor, which overcome the largish steric strain of the dense multiring system. The reported total synthesis also confirms the absolute chemistries of natural (+)-plumisclerin A.
Wound dressing is an important tool for wound management. Designing wound dressings by combining various novel materials and drugs to optimize the peri-wound environment and promote wound healing is a novel concept. Hydrogels feature good ductility, high water content, and favorable oxygen transport, which makes them become some of the most promising materials for wound dressings. In addition, nanomaterials exhibit superior biodegradability, biocompatibility, and colloidal stability in wound healing and can play a role in promoting healing through their nanoscale properties or as carriers of other drugs. By combining the advantages of both technologies, several outstanding and efficient wound dressings have been developed. In this paper, we classify nano-based hydrogel dressings into four categories: hydrogel dressings loaded with a nanoantibacterial drug; hydrogel dressings loaded with oxygen-delivering nanomedicines; hydrogel dressings loaded with nanonucleic acid drugs; and hydrogel dressings loaded with other nanodelivered drugs. The design ideas, advantages, and challenges of these nano-based hydrogel wound dressings are reviewed and analyzed. Finally, we envisaged possible future directions for wound dressings in the context of relevant scientific and technological advances, which we hope will inform further research in wound management.
An efficient method for the synthesis
of new indolizine-fused chromones
has been accomplished from ethyl (E)-3-(2-acetylphenoxy)acrylates
and pyridines in a “one-pot” manner. Facile operation
in open-air, metal-free, and mild conditions renders this protocol
particularly practical and attractive. Moreover, this method can simultaneously
construct two molecular fragments of chromone and indolizine. Scale-up
experiment and the construction of natural products further prove
the practicability of this strategy.
An I2-mediated [3 + 2] annulation of methyl-azaarenes with alkyl 2-isocyanoacetates or amino acid ester hydrochlorides has been demonstrated. This strategy involves the C≡N cleavage of isocyanides and can selectively...
An efficient iodine-imine synergistic
promoted Povarov-type multicomponent
reaction was reported for the synthesis of a practical 2,2′-biquinoline
scaffold. The tandem annulation has reconciled iodination, Kornblum
oxidation, and Povarov aromatization, where the methyl group of the
methyl azaarenes represents uniquely reactive input in the Povarov
reaction. This method has broad substrate scope and mild conditions.
Furthermore, these 2,2′-biquinoline derivatives had been directly
used as bidentate ligands in metal-catalyzed reactions.
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