Decarboxylative Intramolecular Cyclization and Sequential Halogenation of Cyclic Enol Carbonates —Synthesis of Stereochemically-defined Seven-membered Carbocycles—

Rhenium-Catalyzed Decarboxylative Coupling of Cyclic Enol Carbonates with Silyl Enol Ethers and Ketene Silyl Acetals

“…On the other hand, the decarboxylative cyanation took place at the sterically hindered site of 7 . This contrasting regioselectivity might rely on the difference in the reactivity of the nucleophile as mentioned in previous papers. , …”

“… − In the proposed reaction mechanism, the decarboxylation of the cyclic enol carbonate is promoted by a Lewis acid and results in the formation of an oxyallyl cation intermediate or its equivalent. The utility of the oxyallyl cation intermediate was demonstrated by the intramolecular carbon–carbon bond formation reactions, such as the Nazarov cyclization and the homo-Nazarov cyclization, and intramolecular cyclization involving nucleophilic halogenation . Oxyallyl cations are known as electrophiles and studied as a building blocks for the construction of α-functionalized ketones.…”

“…Recently, the Lewis acid-catalyzed decarboxylative transformations of cyclic enol carbonates have been reported by our group (Scheme ). − In the proposed reaction mechanism, the decarboxylation of the cyclic enol carbonate is promoted by a Lewis acid and results in the formation of an oxyallyl cation intermediate or its equivalent. The utility of the oxyallyl cation intermediate was demonstrated by the intramolecular carbon–carbon bond formation reactions, such as the Nazarov cyclization and the homo-Nazarov cyclization, and intramolecular cyclization involving nucleophilic halogenation .…”

Decarboxylative Intramolecular [3 + 2] Cycloaddition of Cyclic Enol Carbonates: Construction of a Bicyclo[3.3.0]octanone Skeleton

“…9 A cyclohexenone was also constructed by the decarboxylative homo-Nazarov cyclization, 10 and a functionalized cycloheptanone was synthesized by intramolecular cyclization involving nucleophilic halogenation. 11 More recently, the decarboxylative transformation was further extended to intermolecular carbon−carbon bond forming reactions, such as allylation 12 and cyanation, 13 coupling with silyl enol ethers. 14 For our proposed reaction mechanism, an oxyallyl cation, generated by the decarboxylation of the cyclic enol carbonates, is the key intermediate, and we envisioned that the oxyallyl cation intermediate could be applied to other ringclosing transformations.…”

“…A wide variety of substrates was demonstrated (Scheme ). A cyclohexenone was also constructed by the decarboxylative homo-Nazarov cyclization, and a functionalized cycloheptanone was synthesized by intramolecular cyclization involving nucleophilic halogenation . More recently, the decarboxylative transformation was further extended to intermolecular carbon–carbon bond forming reactions, such as allylation and cyanation, coupling with silyl enol ethers .…”