Electrophilic chemistry of propargylic alcohols in imidazolium ionic liquids: Propargylation of arenes and synthesis of propargylic ethers catalyzed by metallic triflates [Bi(OTf)3, Sc(OTf)3, Yb(OTf)3], TfOH, or B(C6F5)3
Electrophilic chemistry of propargylic alcohols in imidazolium ionic liquids: Propargylation of arenes and synthesis of propargylic ethers catalyzed by metallic triflates [Bi(OTf)3, Sc(OTf)3, Yb(OTf)3], TfOH, or B(C6F5)3
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DOI：
10.1039/c0ob00872a
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发表时间：
2011-01-01
影响因子：
3.2
通讯作者：
Laali, Kenneth K.
中科院分区：
文献类型：
--
作者：
Aridoss, Gopalakrishnan;Sarca, Viorel D.;Laali, Kenneth K.
固定在咪唑鎓离子液体中的金属三氟甲磺酸盐 M(OTf)(3) (M = Bi, Sc, Yb) [BMIM][BF4]、[BMIM][PF6] 和 [BMIM][OTf] 是炔丙醇 1,3-二苯基-2-丙炔-1-醇 Ia 的一锅反应的有效系统， 1-甲基-3-苯基-2-丙炔-1-醇 Ib 和 2-戊炔-1-醇 Ic，在温和条件下具有多种带有活化取代基的芳烃。 [BMIM][PF6]/B(C6F5)(3)和[BMIM][PF6]/TfOH体系在与Ib和Ic的炔丙基化方面表现优异，而3-苯基-2-丙炔-1-醇Id与活化芳烃的反应导致形成二芳基丙酮。在M(OTf)(3)催化下苯甲醚与Ib的炔丙基化反应具有高度对位选择性，但以TfOH或B(C6F5)(3)为催化剂也可形成邻位异构体。炔丙基部分对底物选择性的空间影响反映在使用炔丙醇Ia对苯酚和乙苯缺乏邻位炔丙基化，以及使用醇Ib显着形成邻位异构体。在后一种情况下，可以通过在 r 下运行反应来提高对位选择性。 t。 10小时。 Bi(OTf)(3) 催化的 1,3-二甲氧基苯与 Ia 的反应导致少量二炔丙基化衍生物以及单炔丙基产物的形成。使用 Sc(OTf)(3) 作为催化剂，反应性较低的芳烃（均三甲苯、乙苯、甲苯）进行炔丙基化，越来越多地导致二炔丙醚和炔丙基酮的形成，而没有与甲苯的环炔丙基化产物。在 Yb(OTf)(3) 催化的 β-萘酚炔丙基化中也观察到伴随形成二炔丙醚，而 2-硝基和 4-硝基苯胺的炔丙基化则导致 N-炔丙基化。 IL 的回收/再利用在代表性案例中得到证实，在 3 个周期内转化率没有明显下降。研究还表明，回收的离子液体可用于将不同的芳香族化合物炔丙化。还证明了 IL/M(OTf)(3) 和 IL/TfOH 系统对两种炔丙醇或炔丙醇与非炔丙醇的杂交和/或自偶联形成多种官能化醚的功效。
Metallic triflates M(OTf)(3) (M = Bi, Sc, Yb), immobilized in imidazolium ionic liquids [BMIM][BF4], [BMIM][PF6] and [BMIM][OTf] are efficient systems for one-pot reactions of propargylic alcohols 1,3-diphenyl-2-propyn-1-ol Ia, 1-methyl-3-phenyl-2-propyn-1-ol Ib, and 2-pentyn-1-ol Ic, with a wide range of arenes bearing activating substituents, under mild conditions. The [BMIM][PF6]/B(C6F5)(3) and [BMIM][PF6]/TfOH systems were superior in propargylation with Ib and Ic, while reaction of 3-phenyl-2-propyn-1-ol Id with activated aromatics resulted in the formation of diaryl-propanones instead. Propargylation of anisole with Ib under M(OTf)(3) catalysis is highly para selective, but with TfOH or B(C6F5)(3) as catalyst the ortho isomer was also formed. Steric influence of the propargylic moiety on substrate selectivity is reflected in the lack of ortho propargylation for phenol and ethylbenzene by using propargylic alcohol Ia, and notable formation of the ortho isomer employing alcohol Ib. In the later case para selectivity could be increased by running the reaction at r. t. for 10 h. The Bi(OTf)(3)-catalyzed reaction of 1,3-dimethoxybenzene with Ia led to minor formation of dipropargylated derivative, along with the monopropargyl product. Propargylation of the less reactive arenes (mesitylene, ethylbenzene, toluene), using Sc(OTf)(3) as catalyst, led increasingly to the formation of dipropargylic ethers and propargyl ketones, with no ring propargylation product with toluene. Concomitant formation of dipropargylic ether was also observed in Yb(OTf)(3)-catalyzed propargylation of beta-naphthol, whereas propargylation of 2-nitro and 4-nitro-aniline led to N-propargylation. The recycling/reuse of the IL was demonstrated in representative cases with no appreciable decrease in the conversions over 3 cycles. It was also shown that recycled IL could be used to propargylate a different aromatic compound. The efficacy of IL/M(OTf)(3) and IL/TfOH systems for cross-breeding two propargylic alcohols or a propargylic alcohol with a non-propargylic alcohol and/or self-coupling, to form a wide variety of functionalized ethers is also demonstrated.