Enantioselective Total Syntheses of Kuwanon X, Kuwanon Y, and Kuwanol A

Abstract

The first enantioselective total syntheses of (-)-kuwanon X, (+)-kuwanon Y, and (+)-kuwanol A have been accomplished by using asymmetric Diels-Alder cycloaddition promoted by chiral VANOL or VAPOL/boron Lewis acid. The biosynthesis-inspired asymmetric Diels-Alder cycloaddition shows high exo selectivity (exo/endo = 13/1), which was unprecedented in the previous total syntheses of related prenylflavonoid Diels-Alder natural products. An acid catalyzed intramolecular ketalization process enabled a biomimetic transformation to construct the polycyclic skeleton of kuwanol A efficiently.

Synthetic self-assembled homogeneous network hydrogels with high mechanical and recoverable properties for tissue replacement

“…35 These hydrogels were synthesized based on the ketalization reaction catalyzed by acid between ketones and alcohols, in which C-O-C ether bond could be constructed by electrophilic rearrangement via removal of water molecule on the mutually reactive functional side-groups (ketone groups and alcoholic hydroxyl groups). 37,38 In this work, the alcoholic hydroxyl side-groups of PVA chain and ketone groups of PVP chain induced the self-assembly in an acid catalysis, obtaining a 1,3-dioxane polymer (Fig. 2a).…”

Current Applications of Suzuki–Miyaura Coupling Reaction in The Total Synthesis of Natural Products: An update

“…Some of them exhibited various biological activities . The asymmetric total synthesis of (‐)‐kuwanon X, (+)‐kuwanon Y, and (+)‐kuwanol A was achieved and reported by Lei and co‐workers in 2016 . In this approach, stereoselective Diels‐Alder cycloaddition catalyzed by chiral VANOL or VAPOL/boron Lewis acid and SMCR are the key steps.…”

“…The latter was reacted with boronate 266 via SMCR using Pd 2 (dba) 3 as catalyst and AsPh 3 as co‐catalyst in DMF to afford diene 267 in 89% yield. Worthy to mention that diene 267 could only be obtained in satisfying yield by SMCR in one‐step, though acetyl re‐protection of the crude mixture (Scheme ) …”

“…[144] The asymmetric total synthesis of (-)-kuwanon X, (+)-kuwanon Y, and (+)kuwanol A was achieved and reported by Lei and coworkers in 2016. [145] In this approach, stereoselective Diels-Alder cycloaddition catalyzed by chiral VANOL or VAPOL/boron Lewis acid and SMCR are the key steps. The total synthesis started with methyl 3,5-dihydroxybenzoate 264 which was converted to tetrahydroxy protected iodide 265 after several steps.…”

“…Worthy to mention that diene 267 could SCHEME 40 Total Synthesis of 8-(6"-Umbelliferyl)apigenin only be obtained in satisfying yield by SMCR in one-step, though acetyl re-protection of the crude mixture (Scheme 42). [145] (+)-Fusarisetin A FN080326 268, a hybrid natural product was initially isolated from the soil fungus Fusarium sp. In 2011 by Osada and co-workers, [146] showed potent inhibition of metastasis in MDA-MB-231 breast cancer cells without momentous cytotoxity.…”