Trifluoroacetic Anhydride Promoted Copper(I)‐Catalyzed Interrupted Click Reaction: From 1,2,3‐Triazoles to 3‐Trifluoromethyl‐Substituted 1,2,4‐Triazinones

Abstract

A copper(I)-catalyzed interrupted click reaction in the presence of trifluoroacetic anhydride has been developed, wherein an N-trifluoroacetyl group is used to accelerate the ring-opening of the putative 5-copper(I) triazolide intermediate. Under the optimized reaction conditions, a broad range of azides and alkynes were found to participate in this transformation, thus affording 3-trifluoromethyl-substituted 1,2,4-triazinones in moderate to excellent yields. The reaction has proven to be compatible with a variety of electron-withdrawing and electron-donating groups, halogens, and nitrogen- and sulfur-containing heterocycles, as well as pharmaceutically relevant molecules.

Highly Stable Copper(I)–Thiacalix[4]arene‐Based Frameworks for Highly Efficient Catalysis of Click Reactions in Water

“…For example, if phenylacetylene reacts with benzyl azide derivatives, the yield can reach 99 %. If the catalytic reactions of benzyl azide with various phenylacetylene derivatives were performed, slightly lower conversions of about 92 and 89 % (Table , entries 7 and 8) were achieved for Cl‐ and Br‐substituted phenylacetylenes, respectively; this may arise due to the steric hindrance effect of the substituted groups …”

“…Afterward, the N3 atom in C interacts with the C4 atom of the alkyne, forming the Cu I –metallacycle ( D ) . In the metallacycle, ring contraction results in intermediate species E . Finally, catalyst 1‐Cl is recovered with the formation of the target product 1,4‐disubstituted 1,2,3‐triazole.…”

“…Phenylacetylene substrates with electron‐withdrawing or ‐donating groups gave high conversions. However, a slightly lower conversion of about 91 % was achieved if OCH 3 ‐substituted phenylacetylene was used as a substrate; this may arise from the steric hindrance effect of the substituted groups …”

Progress in the Synthesis of 1,2,4-Triazines by Tandem Cyclization

“…)存在条件下, 分别原位生 图式 10 两种可能的反应过程 Scheme 10 Two possible reaction processes 同年, Moody 小组 [22] 利用铜卡宾, 通过对酰肼的 N-H 的插入反应来合成 1,2,4-三嗪化合物(Scheme 11). 2017 年, 翁志强小组 [23] 以炔与叠氮化合物为原料, 在三氟乙酸酐促进下, 中断 CuI 催化的 Click 反应, 实现 了 3-三氟甲基-1,2,4-三嗪酮类化合物的合成(Scheme 12). 该反应是基于三氟乙酰基强吸电子性的特点, 将 [24] 在此工作的基础上进一步得 到了 3-全氟烷基取代的 1,2,4-三嗪酮, 例如 3-五氟乙基 化和 3-七氟丙基化产物.…”

Copper-catalyzed chemoselective synthesis of 4-trifluoromethyl pyrazoles

“…As part of our ongoing research into the development of copper-catalyzed reactions for the preparation of organo-uorine compounds, 31,32 we aimed to investigate an alternative protocol for the synthesis of these scaffolds using easy-to-operate synthetic tools. Based on the fact that 3,3,3-triuoropropyne could be generated in situ from a dehydrobromination reaction of readily available 2bromo-3,3,3-triuoropropene (1) under base conditions, 33 and our recent work on 1,3-dipolar cycloaddition reaction, [34][35][36] we wondered if 2-bromo-3,3,3-triuoropropene could be used for the selective synthesis of 4-tri-uoromethyl pyrazoles (Scheme 1d). We report here a new method for the synthesis of 4-triuoromethyl pyrazoles through copper-catalyzed reaction of sydnones with 2bromo-3,3,3-triuoropropene (1).…”