RESUMO
The first total synthesis of isofregenedadiol, a bicyclic diterpene isolated from H. Viscosum, is reported starting from a D-(-)-pantolactone chiral pool. A one-pot quadruple reaction sequence comprising an enyne ring-closing metathesis/cross-metathesis/Diels-Alder/aromatization for the construction of a target skeleton is the highlight of the present synthesis.
Assuntos
Diterpenos/síntese química , Cistaceae/química , Diterpenos/química , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Plantas Medicinais/química , EstereoisomerismoRESUMO
An efficient synthesis of potent molluscicidal agent cyanolide A, a glycosidic 16-membered macrolide, starting from D-(-)-pantolactone is reported. Highly stereoselective aldol, oxa-Michael addition, and Yamaguchi macrolactonization are the key steps in the present synthesis.
Assuntos
4-Butirolactona/análogos & derivados , Macrolídeos/química , Macrolídeos/síntese química , Moluscocidas/química , Moluscocidas/síntese química , 4-Butirolactona/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , EstereoisomerismoRESUMO
Attractive in theory and confirmed to exist, anion-pi interactions have never really been seen at work. To catch them in action, we prepared a collection of monomeric, cyclic and rod-shaped naphthalenediimide transporters. Their ability to exert anion-pi interactions was demonstrated by electrospray tandem mass spectrometry in combination with theoretical calculations. To relate this structural evidence to transport activity in bilayer membranes, affinity and selectivity sequences were recorded. pi-acidification and active-site decrowding increased binding, transport and chloride > bromide > iodide selectivity, and supramolecular organization inverted acetate > nitrate to nitrate > acetate selectivity. We conclude that anion-pi interactions on monomeric surfaces are ideal for chloride recognition, whereas their supramolecular enhancement by pi,pi-interactions appears perfect to target nitrate. Chloride transporters are relevant to treat channelopathies, and nitrate sensors to monitor cellular signaling and cardiovascular diseases. A big impact on organocatalysis can be expected from the stabilization of anionic transition states on chiral pi-acidic surfaces.
Assuntos
Ânions/química , Imidas/química , Transporte de Íons , Bicamadas Lipídicas/química , Modelos Químicos , Modelos Moleculares , Naftalenos/química , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Core-substituted naphthalenediimides (NDIs) are not often used in functional materials despite excellent properties because the harsh conditions used for their synthesis are incompatible with structural diversity. Here, we report rapid access to blue, red, and yellow NDIs under mild conditions with tolerance toward the additional presence of pertinent functional groups.
Assuntos
Fenantrolinas/síntese química , Cristalografia por Raios X , Imidas , Espectroscopia de Ressonância Magnética/métodos , Modelos Moleculares , Estrutura Molecular , Naftalenos , Fenantrolinas/química , EstereoisomerismoRESUMO
A concise and highly enantioselective route has been developed for the synthesis of angucyclinone-type natural products. Utilizing this strategy, total syntheses of five natural products YM-181741, (+)-ochromycinone, (+)-rubiginone B2, (-)-tetrangomycin, and MM-47755 have been accomplished in 22%, 23%, 19%, 18%, and 12% overall yields, respectively. Our approach for the synthesis of these natural products having the benz[a]anthraquinone skeleton is based on a sequential intramolecular enyne metathesis, intermolecular Diels-Alder reaction (DAR), and aromatization. The intramolecular enyne metathesis reaction was employed for the synthesis of enantiopure 1,3-dienes in excellent yields. Furthermore, the synthesis of YM-181741 as well as structurally similar angucyclinones such as (+)-ochromycinone and (+)-rubiginone B2 was achieved via asymmetric enolate alkylation of an oxazolidinone in excellent de. The related angucyclinones (-)-tetrangomycin and MM-47755, bearing a labile tertiary alcohol, were synthesized via Sharpless asymmetric epoxidation of a known allylic alcohol followed by opening the epoxide with Red-Al. The introduction of oxygen functionality at C-1 in all these natural products was accomplished by photooxygenation under a positive pressure of oxygen.
Assuntos
Antraquinonas/síntese química , Antibacterianos/síntese química , Antibacterianos/química , Benzo(a)Antracenos/síntese química , Química Orgânica/métodos , Química Farmacêutica/métodos , Desenho de Fármacos , Modelos Químicos , Oxigênio/química , EstereoisomerismoRESUMO
An enantioselective route for the synthesis of oxatetracyclic core of platensimycin is reported for the first time using a 5-exo-trig cyclization followed by intramolecular etherification as key reactions. The requisite dienynone for the radical cyclization is synthesized in eight steps from the Wieland-Miescher ketone employing a Claisen rearrangement.
Assuntos
Adamantano/química , Adamantano/síntese química , Aminobenzoatos/química , Aminobenzoatos/síntese química , Anilidas/química , Anilidas/síntese química , Ciclização , Conformação Molecular , EstereoisomerismoRESUMO
A new class of sugar-oxasteroid-quinone hybrid molecules has been designed and synthesized involving an efficient enyne metathesis/Diels-Alder reaction strategy.
