- Stereospecific Nickel-Catalyzed Reductive Cross-Coupling of Alkyl Tosylate and Allyl Alcohol Electrophiles
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The stereospecific cross-coupling of easily accessed electrophiles holds significant promise in the construction of C-C bonds. Herein, we report a nickel-catalyzed reductive coupling of allyl alcohols with chiral, nonracemic alkyl tosylates. This cross-coupling delivers valuable allylation products with high levels of stereospecificity across a range of substrates. The catalytic system consists of a simple nickel salt in conjunction with a commercially available reductant and importantly represents a rare example of a cross-coupling involving the C-O bonds of two electrophiles.
- Alexanian, Erik J.,Tercenio, Quentin D.
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p. 7215 - 7219
(2021/09/22)
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- Two-Step Protocol for Iodotrimethylsilane-Mediated Deoxy-Functionalization of Alcohols
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We have developed a two-step protocol for iodotrimethylsilane-mediated deoxy-functionalization of primary and secondary alcohols to afford products containing a C?N, C?S, or C?O bond. In the first step the alcohol undergoes iodination with iodotrimethylsilane, and in the second, the iodine atom is replaced by a N, S, or O nucleophile. Compared with traditional Mitsunobu reaction, non-acidic pre-nucleophiles can be used, and the reaction proceeds with retention of configuration. This operationally simple, highly efficient protocol can be used for some natural products and small-molecule drugs containing hydroxy-group.
- Chen, Yuming,He, Ru,Song, Hongjian,Yu, Guoqing,Li, Chenglin,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 1179 - 1183
(2021/02/01)
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- Preparation method of labetalol hydrochloride
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The invention provides a preparation method of labetalol hydrochloride, and belongs to the technical field of medicines. The invention provides a preparation method. The method comprises the following steps: carrying out nucleophilic substitution reaction on 5-halogenated acetyl salicylamide serving as an initial raw material and benzylamine, and then carrying out nucleophilic substitution reaction on the obtained product and 3-halogenated butylbenzene (or carrying out amine-ester exchange reaction on the obtained product and an esterification reaction product of 3-hydroxybutylbenzene and p-toluenesulfonyl chloride); and carrying out catalytic hydrogenation reaction and salifying to obtain the labeolol hydrochloride. According to the preparation method provided by the invention, benzylamine is adopted to replace dibenzylamine, so that the raw materials are high in atom utilization rate and environment-friendly, and atom economy of green chemistry is embodied; wherein the amine-ester exchange reaction is high in selectivity, and the obtained product is directly used for the next-step reaction. The one-step method is adopted to remove the protective agent and reduce carbonyl, so that the process route is shortened; meanwhile, the preparation method is simple and convenient to operate, high in stability and controllability, high in production cost, high in yield and suitable for industrial production.
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Paragraph 0084; 0086-0087
(2021/11/27)
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- Deoxyfluorination with CuF2: Enabled by Using a Lewis Base Activating Group
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Deoxyfluorination is a primary method for the formation of C?F bonds. Bespoke reagents are commonly used because of issues associated with the low reactivity of metal fluorides. Reported here is the development of a simple strategy for deoxyfluorination, using first-row transition-metal fluorides, and it overcomes these limitations. Using CuF2 as an exemplar, activation of an O-alkylisourea adduct, formed in situ, allows effective nucleophilic fluoride transfer to a range of primary and secondary alcohols. Spectroscopic investigations have been used to probe the origin of the enhanced reactivity of CuF2. The utility of the process in enabling 18F-radiolabeling is also presented.
- Bode, Bela E.,Chabbra, Sonia,Champion, Sue,Dawson, Daniel M.,Sood, D. Eilidh,Sutherland, Andrew,Watson, Allan J. B.
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supporting information
p. 8460 - 8463
(2020/04/10)
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- Cobalt-Catalyzed Aminocarbonylation of Alkyl Tosylates: Stereospecific Synthesis of Amides
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Metal-catalyzed aminocarbonylation is a standard approach for installing amide functionality in chemical synthesis. Despite broad application of this transformation using aryl or vinyl electrophiles, there are few examples involving unactivated aliphatic substrates. Furthermore, there are no stereocontrolled aminocarbonylations of alkyl electrophiles known. Herein, we report a stereospecific aminocarbonylation of unactivated alkyl tosylates for the synthesis of enantioenriched amides. This cobalt-catalyzed transformation uses a remarkably broad range of amines and proceeds with excellent stereospecificity and chemoselectivity.
- Sargent, Brendon T.,Alexanian, Erik J.
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p. 9533 - 9536
(2019/06/24)
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- Manganese-Catalyzed Stereospecific Hydroxymethylation of Alkyl Tosylates
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The development of a stereospecific hydroxymethylation of alkyl tosylates using an inexpensive, first-row catalyst is described. The transformation proceeds under mild conditions with low pressure to deliver homologated alcohols as products. Chiral, nonracemic β-branched primary alcohols are obtained with high enantiospecificity from easily accessed secondary alkyl substrates. Simple modification of the reaction system also permits access to α-d2 alcohols. These studies use anionic metal carbonyl catalysis to access a synthetic equivalent of the challenging hydroxymethyl anion from carbon monoxide.
- Shenouda, Hannah,Alexanian, Erik J.
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p. 9268 - 9271
(2019/11/19)
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- Use of the 2-Pyridinesulfonyloxy Leaving Group for the Fast Copper-Catalyzed Coupling Reaction at Secondary Alkyl Carbons with Grignard Reagents
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Investigation of the copper-catalyzed coupling reaction of 2-pyridinesulfonates with Grignard reagents revealed that reactions with catalytic Cu(OTf)2 were completed in 40 min. The results differed from those of the previous CuI-catalyzed reactions of tosylates in the presence of additives (LiOMe and TMEDA) for 12-24 h. It was shown that the preferred coordination of the leaving group to the reagents accelerated the reaction. Successful reagents were MeMgCl and other RMgX. Complete inversion was established.
- Shinohara, Riku,Morita, Masao,Ogawa, Narihito,Kobayashi, Yuichi
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supporting information
p. 3247 - 3251
(2019/05/10)
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- Cobalt-Catalyzed Carbonylative Cross-Coupling of Alkyl Tosylates and Dienes: Stereospecific Synthesis of Dienones at Low Pressure
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Despite advances in organometallic cross-coupling of alkyl electrophiles, there are few stereoselective reactions of chiral, nonracemic substrates. Herein we report a stereospecific carbonylative coupling of alkyl tosylates and dienes producing enantioenriched dienones. This catalytic process proceeds under low pressure and mild conditions using a simple cobalt catalyst and extends to diverse tosylate and diene coupling partners. The transformation constitutes a unique, convergent approach to the asymmetric synthesis of valuable carbonyl compounds from easily accessed starting materials.
- Sargent, Brendon T.,Alexanian, Erik J.
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supporting information
p. 12438 - 12440
(2017/09/25)
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- Stereocontrolled C(sp3)-P bond formation with non-activated alkyl halides and tosylates
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The C(sp3)-P bond is formed via the reaction between P-H compounds and non-activated alkyl electrophiles, especially secondary alkyl halides and tosylates. This reaction proceeds via an SN2 mechanism with inversion of configuration, so it can be used to form C-P bonds with stereocontrol from chiral secondary alcohols.
- Yang, Chu-Ting,Han, Jun,Liu, Jun,Li, Yi,Zhang, Fan,Gu, Mei,Hu, Sheng,Wang, Xiaolin
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p. 24652 - 24656
(2017/07/11)
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- Cobalt-Catalyzed Silylcarbonylation of Unactivated Secondary Alkyl Tosylates at Low Pressure
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A catalytic preparation of silyl enol ethers from unactivated secondary alkyl tosylates is reported. An inexpensive cobalt catalyst is used under mild conditions with low pressures of carbon monoxide. Nucleophilic, anionic cobalt carbonyls facilitate the catalytic activation of a range of alkyl tosylates. The silylcarbonylation offers a practical approach to synthetically valuable silyl enol ethers from simple starting materials.
- Roque Pena, Joan E.,Alexanian, Erik J.
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supporting information
p. 4413 - 4415
(2017/09/11)
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- A simple route to 1,4-addition reactions by Co-catalyzed reductive coupling of organic tosylates and triflates with activated alkenes
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An efficient Co-catalyzed 1,4-addition reaction of alkyl/aryl triflates and tosylates with activated alkenes is described. In this reaction, an air-stable cobalt(ii) complex, a mild reducing agent Zn and a simple proton source (H2O) are used. A radical mechanism for the addition of alkyl tosylates to activated alkenes is likely involved.
- Hsieh, Jen-Chieh,Chu, Yi-Hua,Muralirajan, Krishnamoorthy,Cheng, Chien-Hong
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supporting information
p. 11584 - 11587
(2017/10/27)
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- Copper-Catalyzed Reductive Cross-Coupling of Nonactivated Alkyl Tosylates and Mesylates with Alkyl and Aryl Bromides
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A copper-catalyzed reductive cross-coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost-effective construction of aryl-alkyl and alkyl-alkyl C=C bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo- or heterocycles, such as 2,3-dihydrobenzofuran and benzochromene derivatives.
- Liu, Jing-Hui,Yang, Chu-Ting,Lu, Xiao-Yu,Zhang, Zhen-Qi,Xu, Ling,Cui, Mian,Lu, Xi,Xiao, Bin,Fu, Yao,Liu, Lei
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supporting information
p. 15334 - 15338
(2016/02/18)
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