Synthesis of trans,trans,cis-fused tetracyclic skeleton via radical domino cyclization

Research progress of meliaceous limonoids from 2011 to 2021

“…Cascade cyclization reactions provides a quick access to the ring-intact limonoid azadiradione framework from corresponding linear precursors, thereby significantly increasing the molecular complexity in a single step. By taking advantage of this strategy, A/B/C/D and B/C/D/E molecular fragments were completed by Yamashita, 441 Inoue, 442 Shoji, 443 and González 444 (Scheme 10).…”

Recent Developments in Polyene Cyclizations and Their Applications in Natural Product Synthesis

“…In 2017, Shoji and co-workers reported a radical cyclization of β-keto ester 194 which was mediated by Mn(III)/Cu(II) to give tetracyclic ketone 196 (11%) and tricyclic ketone 197, as a mixture of regioisomers (22%) via intermediate 195 (Scheme 38). 48 The functionalization arose from tuning the electron-donating or -demanding properties of the polyene scaffold to allow efficient cyclization between alternating electrophilic radicals with electron-rich trisubstituted olefins.…”

Rearrangement of Methylenebis(cyclohexane-1,3-dione) Enols Induced by Mn(III)-Catalyzed Aerobic Oxidation

“…Among them, 1,3-dicarbonyl enolates are the most powerful and convenient chemical species for organic synthesis . We have studied the chemistry of the 1,3-dicarbonyl enolate radicals produced by Mn­(III)-mediated oxidation and synthesized many unique organic molecules. , Recently, we reported carbon–carbon bond formation and cyclization using the reactions of tricarbonyl and tetracarbonyl systems, for example, the reaction of 2-oxoethyl-1,3-dicarbonyl compounds with alkenes, which produced dihydropyrans and tetrahydrofuro­[2,3- b ]­furans, and the reaction of methylenebis­(cyclohexanedione)­s, which selectively gave spirodihydrofurans and dispirocyclopropanes . On the other hand, the Mn­(III)-catalyzed aerobic oxidation of 1,3-dicarbonyl enolates led to endoperoxidation and hydroperoxidation reactions .…”