Palladium-Catalyzed Oxidative Cyclization of α-Allenols in the Presence of TBN: Access to 3(2H)-Furanones

Abstract

A new palladium-catalyzed oxidative cyclization of α-allenols is described. The readily accessible α-allenols participate in intra-molecular oxidative cyclization in the presence of TBN to grant access to multisubstituted 3(2H)-furanones, which are common motifs in several biologically important natural products and pharmaceuticals.

δ-Acetoxy Allenoate as a 5C-Synthon in Domino-Annulation with Sulfamidate Imines: Ready Access to Coumarins

“…In the past few decades, allenes have been extensively explored in cyclization reactions. , Among the substituted allenes, allenoates have found numerous applications in Lewis base-directed cycloaddition/annulation reactions via zwitterionic intermediates by taking Lu’s [3 + 2] cycloaddition as an inspirational finding. − The readily detachable -OAc group in acetoxy allenoates renders this class of compounds as valuable synthons by generating key diene-ammonium/phosphonium intermediates . In Lewis base-mediated/catalyzed annulations, δ-acetoxy allenoates can offer 5–8-membered ring scaffolds by the attack of the nucleophile at the δ- or α-carbon of an electrophilic intermediate, wherein the allenoate part offers 1C - 4C for the framework, but so far none of them utilized acetoxy allenoates as 5C- synthons (Scheme a–b) .…”

Synthesis of 3(2H)-furanone derivatives: p-TsOH/halotrimethylsilane promoted cycloketonization of γ-hydroxyl ynones

“…3 Notably, many of these endeavors have reported the utilization of transition metal catalysts for the synthesis of 3(2 H )-furanones. 4 Nevertheless, the pursuit of environmentally friendly practices and sustainable development has steered synthetic chemists towards the continual exploration of innovative strategies and methodologies that align with the principles of green synthesis. 5 In 2022, Chen and Fang reported a noteworthy advancement by introducing an I 2 -catalyzed oxa-Nazarov cyclization-Michael addition of vinyl α -diketones and enones, which facilitated the synthesis of a range of functionalized 3(2 H )-furanones (Scheme 1A).…”

Copper(I)-Catalyzed Nitrosylation/Annulation Cascade of Enaminones with tert-Butyl Nitrite: Access to 1H-1,2,3-Triazole 2-Oxides

“…In recent years, tert-butyl nitrite (TBN) has been applied as a convenient and effective nitration reagent. 13 Utilization of TBN as a versatile nitrogen source for the construction of Nheterocycles has become one of the most attractive synthetic targets. As a matter of fact, TBN has been applied in the synthesis of 2H-azirines 14 and triazoles 15 as an N source and in the direct preparation of quinoxaline N-oxides 16 and isoxazoles 17 as a convenient NO source.…”