Iodine-Catalyzed Synthesis of Substituted Furans and Pyrans: Reaction Scope and Mechanistic Insights
作者:Domenic P. Pace、Raphaël Robidas、Uyen P. N. Tran、Claude Y. Legault、Thanh Vinh Nguyen
DOI:10.1021/acs.joc.1c00608
日期:2021.6.18
Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furansusing molecular iodine, a simple and inexpensive catalyst. The method described is performed under solvent-free conditions at an ambient temperature and atmosphere,
Controllable Access to Furans and Dihydrofurans through Cyclization/Coupling of Internal Acetylenic β‐Ketoesters with Aryl Bromides
作者:Bartosz Bisek、Wojciech Chaładaj
DOI:10.1002/adsc.202200686
日期:2022.12.20
Pd-catalyzed tandem cyclization/coupling of internal β-propargylic-β-ketoesters with (hetero)aryl bromides is described. Two protocols are established which selectively lead to 2-benzylidene-dihydrofurans, when isomerization is inhibited under mild conditions (temp. ≤40 °C and weak base – K2CO3), or to 2-benzyl-furans when base-induced aromatization is enabled. A catalytic cycle involving oxidative
描述了 Pd 催化的内部 β-炔丙基-β-酮酯与(杂)芳基溴化物的串联环化/偶联。建立了两种方案,当异构化在温和条件下(温度≤40 °C 和弱碱 – K 2 CO 3)被抑制时,选择性地产生 2-亚苄基-二氢呋喃,或在碱诱导芳构化时产生 2-苄基-呋喃已启用。基于详细的实验和理论研究,提出了涉及氧化加成、用炔取代溴化物、限速反选择性5-exo-dig氧环化随后氧鎓中间体快速去质子化和还原消除的催化循环。
Reactivity of vinylidene-π-allyl palladium(<scp>ii</scp>) species
作者:Can Li、Zhengnan Zhou、Yuling Li、Yinlong Guo、Shengming Ma
DOI:10.1039/d2cc06871k
日期:——
The reactivity of a new type of organometallicintermediate, vinylidene-π-allyl palladium species, has been demonstrated: the reaction between 4-alken-2-ynyl carbonates and stabilized carbon nucleophiles afforded functionalized 1,2,3,-butatriene compounds in moderate to high yields and excellent regioselectivities.
Access to 2-Alkenyl-furans via a Cascade of Pd-Catalyzed Cyclization/Coupling Followed by Oxidative Aromatization with DDQ
作者:Bartosz Bisek、Wojciech Chaładaj
DOI:10.1021/acs.joc.4c00149
日期:2024.5.17
An unprecedented DDQ-mediated oxidative aromatization of 2-bezylidene-dihydrofurans yielding 2-alkenyl-furans is disclosed. Integration of this transformation with a prior Pd-catalyzed reaction of α-propargylic-β-ketoesters and (hetero)aryl halides into a one-pot cascade process opens a direct modular route to highly substituted 2-vinyl-furans. Experimental and computational studies reveal that the
Pd-catalyzed cycloisomerization–allylation of 4-alkynones: synthesis of 5-homoallylfuran derivatives
作者:Akio Saito、Yohei Enomoto、Yuji Hanzawa
DOI:10.1016/j.tetlet.2011.06.037
日期:2011.8
In the presence of Pd-2(dba)(3)-fBu(3)P catalyst and Cs2CO3, cycloisomerization-allylation reactions of 4-alkynone derivatives with allyl carbonates in MeCN proceed in 5-exo mode to give highly-substituted furans having homoallyl groups at 5-position. (C) 2011 Elsevier Ltd. All rights reserved.