Room-Temperature Synthesis of 1,3,5-Tri(het)aryl Benzene from Nitroalkenes Using Pd(OAc)₂: Complete Mechanistic and Theoretical Studies

Abstract

Herein, a room-temperature catalytic pathway for 1,3,5-tri­(het)­aryl derivatives from nitroalkenes using simple Pd­(OAc)2 is presented. This newly developed C–C bond-forming methodology takes place in a cascade manner with the initial pallado-Morita–Baylis–Hillman (MBH) type adduct. The broad substrate scopes, functional group tolerance, and different aryl-substituted benzene derivatives make this methodology more attractive. Furthermore, the mechanistic understanding through isolation of intermediates and DFT studies of the catalytic cycle provide requisite insight into the methodology.

Pd‐Catalyzed Tandem Pathway for Stereoselective Synthesis of (E)‐1,3‐Enyne from β‐Nitroalkenes by Using a Sacrificial Directing Group

“…Screening of common solvents, such as DMSO, CH 3 CN, toluene, THF, and 1,4‐dioxane proceeded the reaction with moderate to low yield and selectivity, and DMF was found to be best for this present cross‐coupling reaction of two alkenes (Table 1, entry 8–9; see Supporting Information). Reaction at higher temperature (80 °C) reduced the formation of conjugated 1,3‐enyne 3 a but increased tri‐substituted benzene product formation [64] . Notably, absence of additive (NaOAc) closedown the conversion, suggesting the fundamental involvement of acetate ion in the tandem catalytic pathway and the presence of palladium catalyst to deliver excellent reactivity and selectivity manifest the cooperative interaction between nitro group and palladium catalyst.…”

“…Reaction at higher temperature (80 °C) reduced the formation of conjugated 1,3-enyne 3 a but increased tri-substituted benzene product formation. [64] Notably, absence of additive (NaOAc) closedown the conversion, suggesting the fundamental involvement of acetate ion in the tandem catalytic pathway and the presence of palladium catalyst to deliver excellent reactivity and selectivity manifest the cooperative interaction between nitro group and palladium catalyst. After thoughtful examinations, 1 equiv of 1 a, 1.2 equiv of 2 a, 0.75 equiv of NaOAc and 5 mol % of Pd(TFA) 2 in DMF were found to be the optimal conditions for the synthesis of (E)-pent-3-en-1-yne-1,4diyldibenzene (3 a) (Table 1, entry 11).…”

An overview of the synthetic strategies ofC3-symmetric polymeric materials containing benzene and triazine cores and their biomedical applications

“… 27 Furthermore, S. Midya reported a room-temperature catalytic pathway for benzene derivatives with C 3-symmetry from nitroalkenes in the presence of Pd(OAc) 2 ( Table 1 , entry 2-c). 29 …”

“…Palladium-catalyzed formation of tri-substituted benzene derivatives with C3-symmetry from alkenes bearing electronwithdrawing groups has been reported frequently. [26][27][28][29] Tamaso et al developed a triannelation reaction by Pd(OAc) 2 , HPMo 8 V 4 , acetalization of acrylate with methanol, followed by trimerization reaction of the acetal by CeCl 3 (Table 1, entry 2a). 26 Withal, a facile palladium catalyst system was developed for the highly regioselective cyclotrimerization of olens bearing electron-withdrawing groups in PdCl 2 /O 2 /DMF (Table 1, entry 1-b).…”

Research Progress on Reactions Involving β-Nitrostyrene

“…故 Ghosh 课题组 [15] 在 2022 年报道了室温下钯催化 β-硝 基烯烃环化生成不同的三芳基苯衍生物的反应. 后者宽 泛的底物范围和优异的官能团耐受性以及没有大量的 废弃物产生, 使得其在各种研究领域具有很高的潜在实 用性(Eq.…”