- Umpolung Strategy for Arene C?H Etherification Leading to Functionalized Chromanes Enabled by I(III) N-Ligated Hypervalent Iodine Reagents
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The direct formation of aryl C?O bonds via the intramolecular dehydrogenative coupling of a C?H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C?H etherification via an umpoled alcohol cyclization mediated by an I(III) N-HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization-iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O-intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2-shift pathways. (Figure presented.).
- Mikhael, Myriam,Guo, Wentao,Tantillo, Dean J.,Wengryniuk, Sarah E.
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supporting information
p. 4867 - 4875
(2021/09/14)
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- Preparation method of alkyl nitrile compound
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The invention discloses a preparation method of an alkyl nitrile compound shown as formula I. The preparation method comprises the following step: in a solvent, in the presence of an additive and a catalyst, Zn (CN) 2 and an alkyl halide shown as formula II are subjected to a coupling reaction as shown in the specification to obtain the alkyl nitrile compound as shown in the formula I, wherein theadditive comprises an alkali, the catalyst comprises a nickel compound and a phosphine ligand; the nickel compound is one or more of zero-valent nickel, monovalent nickel salt and divalent nickel salt; when the nickel compound contains zero-valent nickel or divalent nickel salt, the catalyst further comprises a reducing agent. According to the preparation method disclosed by the invention, cyanation of an alkyl halide can be simply, conveniently and efficiently realized by using a cheap catalytic system, and the preparation method also has good functional group compatibility and substrate universality.
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Paragraph 0141-0143
(2020/05/14)
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- Nickel-Catalyzed Cyanation of Unactivated Alkyl Chlorides or Bromides with Zn(CN)2
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A nickel-catalyzed cyanation of unactivated secondary alkyl chlorides or bromides using less toxic Zn(CN)2 as the cyanide source has been developed. The reaction features the use of air-stable and inexpensive NiCl2·6H2O or Ni(acac)2 as the precatalysts and offers an efficient synthesis of a broad range of alkyl nitriles. Cyanation of primary alkyl chlorides or bromides was also achieved by reaction with Zn(CN)2 in the presence of n-Bu4NCl without the need of nickel catalyst.
- Xia, Aiyou,Xie, Xin,Chen, Haoyi,Zhao, Jidong,Zhang, Chunli,Liu, Yuanhong
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supporting information
p. 7735 - 7739
(2019/01/03)
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- Investigation of the Deprotonative Generation and Borylation of Diamine-Ligated α-Lithiated Carbamates and Benzoates by in Situ IR spectroscopy
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Diamine-mediated α-deprotonation of O-alkyl carbamates or benzoates with alkyllithium reagents, trapping of the carbanion with organoboron compounds, and 1,2-metalate rearrangement of the resulting boronate complex are the primary steps by which organoboron compounds can be stereoselectively homologated. Although the final step can be easily monitored by 11B NMR spectroscopy, the first two steps, which are typically carried out at cryogenic temperatures, are less well understood owing to the requirement for specialized analytical techniques. Investigation of these steps by in situ IR spectroscopy has provided invaluable data for optimizing the homologation reactions of organoboron compounds. Although the deprotonation of benzoates in noncoordinating solvents is faster than that in ethereal solvents, the deprotonation of carbamates shows the opposite trend, a difference that has its origin in the propensity of carbamates to form inactive parasitic complexes with the diamine-ligated alkyllithium reagent. Borylation of bulky diamine-ligated lithiated species in toluene is extremely slow, owing to the requirement for initial complexation of the oxygen atoms of the diol ligand on boron with the lithium ion prior to boron-lithium exchange. However, ethereal solvent, or very small amounts of THF, facilitate precomplexation through initial displacement of the bulky diamines coordinated to the lithium ion. Comparison of the carbonyl stretching frequencies of boronates derived from pinacol boronic esters with those derived from trialkylboranes suggests that the displaced lithium ion is residing on the pinacol oxygen atoms and the benzoate/carbamate carbonyl group, respectively, explaining, at least in part, the faster 1,2-metalate rearrangements of boronates derived from the trialkylboranes.
- Mykura, Rory C.,Veth, Simon,Varela, Ana,Dewis, Lydia,Farndon, Joshua J.,Myers, Eddie L.,Aggarwal, Varinder K.
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supporting information
p. 14677 - 14686
(2018/11/20)
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- Tandem Cross Coupling Reaction of Alcohols for Sustainable Synthesis of β-Alkylated Secondary Alcohols and Flavan Derivatives
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A Ru(II) NHC complex (loading down to 0.001 mol%) catalyzed cross coupling of a broad range of aromatic, aliphatic and heterocyclic alcohols is reported. This protocol also functioned efficiently under solvent-free conditions. Remarkably, this catalytic system disclosed so far the highest TON of 288000 for the cross coupling of alcohols. Notably, this methodology was successfully applied for the one-pot synthesis of a range of flavan derivatives. A detailed DFT studies and kinetic experiments were performed to understand the reaction mechanism as well as the high reactivity of this catalytic system. (Figure presented.).
- Shee, Sujan,Paul, Bhaskar,Panja, Dibyajyoti,Roy, Bivas Chandra,Chakrabarti, Kaushik,Ganguli, Kasturi,Das, Ayan,Das, Gourab Kanti,Kundu, Sabuj
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supporting information
p. 3888 - 3893
(2017/10/07)
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- Bifunctional Ru(II) complex catalysed carbon-carbon bond formation: an eco-friendly hydrogen borrowing strategy
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The atom economical borrowing hydrogen methodology enables the use of alcohols as alkylating agents for selective C-C bond formation. A bifunctional 2-(2-pyridyl-2-ol)-1,10-phenanthroline (phenpy-OH) based Ru(ii) complex (2) was found to be a highly efficient catalyst for the one-pot β-alkylation of secondary alcohols with primary alcohols and double alkylation of cyclopentanol with different primary alcohols. Exploiting the metal-ligand cooperativity in complex 2, several aromatic, aliphatic and heteroatom substituted alcohols were selectively cross-coupled in high yields using significantly low catalyst loading (0.1 mol%). An outer-sphere mechanism is proposed for this system as exogenous PPh3 has no significant effect on the rate of the reaction. Notably, this is a rare one-pot strategy for β-alkylation of secondary alcohols using a bifunctional Ru(ii)-complex. Moreover, this atom-economical methodology displayed the highest cumulative turn over frequency (TOF) among all the reported transition metal complexes in cross coupling of alcohols.
- Chakrabarti, Kaushik,Paul, Bhaskar,Maji, Milan,Roy, Bivas Chandra,Shee, Sujan,Kundu, Sabuj
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p. 10988 - 10997
(2016/12/06)
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- Bifunctional RuII-Complex-Catalysed Tandem C?C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents
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Catalytic activities of a series of functional bipyridine-based RuIIcomplexes in β-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional RuIIcomplex (3 a) bearing 6,6’-dihydroxy-2,2’-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon?carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal–ligand cooperative RuIIsystem. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction.
- Roy, Bivas Chandra,Chakrabarti, Kaushik,Shee, Sujan,Paul, Subhadeep,Kundu, Sabuj
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supporting information
p. 18147 - 18155
(2016/12/16)
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- Examining the origin of selectivity in the reaction of racemic alcohols with chiral N-phosphoryl oxazolidinones
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A range of known and novel N-phosphoryl oxazolidinones and imidazolidinones were prepared and screened in the kinetic resolution of a range of racemic magnesium chloroalkoxides. Models are proposed to account for the enantioselectivity achieved based on a combination of chiral relay effects, generation of transient stereochemistry and the structure of the intermediate magnesium alkoxide.
- Crook, Samuel,Parr, Nigel J.,Simmons, Jonathan,Jones, Simon
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p. 1298 - 1308
(2015/01/09)
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- Iron-catalyzed intramolecular allylic C-H amination
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A highly selective C-H amination reaction under iron catalysis has been developed. This novel system, which employs an inexpensive, nontoxic [Fe IIIPc] catalyst (typically used as an industrial ink additive), displays a strong preference for allylic C-H amination over aziridination and all other C-H bond types (i.e., allylic > benzylic > ethereal > 3° > 2° ? 1°). Moreover, in polyolefinic substrates, the site selectivity can be controlled by the electronic and steric character of the allylic C-H bond. Although this reaction is shown to proceed via a stepwise mechanism, the stereoretentive nature of C-H amination for 3° aliphatic C-H bonds suggests a very rapid radical rebound step.
- Paradine, Shauna M.,White, M. Christina
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supporting information; scheme or table
p. 2036 - 2039
(2012/03/11)
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- Use of alkyl 2,4,6-triisopropylbenzoates in the asymmetric homologation of challenging boronic esters
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(-)-Sparteine induced lithiation of primary 2,4,6-triisopropylbenzoates and subsequent homologation of boronic esters is reported. A comparative study with lithiated N,N-diisopropylcarbamates has demonstrated the superiority of the hindered benzoate. The Royal Society of Chemistry 2011.
- Larouche-Gauthier, Robin,Fletcher, Catherine J.,Couto, Irantzu,Aggarwal, Varinder K.
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supporting information; experimental part
p. 12592 - 12594
(2012/01/05)
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- N-heterocyclic carbene-catalyzed hydrosilylation of styryl and propargylic alcohols with dihydrosilanes
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Reducing alkenes to tears: Addition of structurally diverse N-heterocyclic carbenes (NHCs) to silicon allows the reduction of propargylic and styryl alcohols through an organocatalyzed silylation/direct hydride transfer tandem reaction (see scheme). Catalytic turnover is enabled by the switch to and from hypervalent silicon. This provides a new synthetic application of NHC-main group element complexes. Copyright
- Zhao, Qiwu,Curran, Dennis P.,Malacria, Max,Fensterbank, Louis,Goddard, Jean-Philippe,Lacote, Emmanuel
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supporting information; experimental part
p. 9911 - 9914
(2011/10/05)
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- Chemoselective conjugate reduction of α,β-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media
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Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C-O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C-O to C-C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones. Now we have found that a variety of α,β-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.
- Li, Xuefeng,Li, Liangchun,Tang, Yuanfu,Zhong, Ling,Cun, Linfeng,Zhu, Jin,Liao, Jian,Deng, Jingen
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supporting information; experimental part
p. 2981 - 2988
(2010/07/05)
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- Indium-copper and indium-silver mediated Barbier-Grignard-type alkylation reaction of aldehydes using unactivated alkyl halides in water
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(Chemical Equation Presented) An efficient method has been developed for the Barbier-Grignard-type alkylation reaction of aldehydes (including aliphatic version) using unactivated alkyl halides in water in the presence of an In/CuI/I2 or In/AgI/I2 system. The reactions proceeded more efficiently in water than in organic solvent. In, CuI or AgI, and I 2 were all essential for the efficient progress of the reactions. A radical-type reaction mechanism was studied and proposed by using 4-pentenal as substrate.
- Shen, Zhi-Liang,Yeo, Yan-Lin,Loh, Teck-Peng
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p. 3922 - 3924
(2008/09/19)
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- Lithiated carbamates: Chiral carbenoids for iterative homologation of boranes and boronic esters
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(Chemical Equation Presented) Take your pick: Either enantiomer of either diastereomer of substrates bearing adjacent stereogenic centers is accessible through reaction of an (R)- or (S)-lithiated carbamate with an (R)- or (S)-boronic ester (see scheme; pin = pinacolate, OCb = substituted carbamate).
- Stymiest, Jake L.,Dutheuil, Guillaume,Mahmood, Adeem,Aggarwal, Varinder K.
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p. 7491 - 7494
(2008/09/17)
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- Direct β-alkylation of secondary alcohols with primary alcohols catalyzed by a Cp*Ir complex
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(Chemical Equation Presented) A new catalytic system for β-alkylation of secondary alcohols has been developed. In the presence of [Cp*IrCl 2]2 (Cp* = pentamethylcyclopentadienyl) catalyst and base, the reactions of various secondary alcohols with primary alcohols give β-alkylated higher alcohols in good to excellent yields without any hydrogen acceptor or hydrogen donor. This reaction proceeds via successive hydrogen-transfer reactions and aldol condensation.
- Fujita, Ken-Ichi,Asai, Chiho,Yamaguchi, Tetsuhiro,Hanasaka, Fumihiro,Yamaguchi, Ryohei
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p. 4017 - 4019
(2007/10/03)
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- A reaction for sp3-sp3 C-C bond formation via cooperation of Lewis acid-promoted/Rh-catalyzed C-H bond activation
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A new method for intermolecular sp3-sp3 C-C bond formation between primary aliphatic alcohol and olefin by use of a RhCl(PPh3)3 (cat.)/BF3·OEt2 (2.5 equiv)/BuBr (0.5 equiv)/toluene system was first disclosed, which possessed quite significant utilities for organic synthesis, especially for that of secondary alcohols. The most significant aspect is the discovery that rhodium-catalyzed C-H bond activation of alcohols is feasible under Lewis acid-promoted conditions. Copyright
- Shi, Lei,Tu, Yong-Qiang,Wang, Min,Zhang, Fu-Min,Fan, Chun-An,Zhao, Yu-Ming,Xia, Wu-Jiong
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p. 10836 - 10837
(2007/10/03)
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- Lewis Acids Catalyze the Addition of Allylboronates to Aldehydes by Electrophilic Activation of the Dioxaborolane in a Closed Transition Structure
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This study addressed the mechanism of the recently reported Lewis acid-catalyzed manifold for additions of allylboronates to aldehydes. A series of control experiments using various reagents and conditions, and kinetic studies by low-temperature NMR spectroscopy, were performed to investigate the origin of the activation provided by the best catalyst, Sc(OTf)3. The results obtained are strongly supportive of a mechanism involving electrophilic boron activation by coordination of the metal ion to one of the boronate oxygens in a closed bimolecular transition state. Copyright
- Rauniyar, Vivek,Hall, Dennis G.
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p. 4518 - 4519
(2007/10/03)
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- Reduction of α,β unsaturated carbonyl compounds by Ni2+-BH-4
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The reduction of α,β unsaturated carbonyl compounds by sodiumborohydride is catalysed by Ni(bpy)Cl2 (bpy = 2,2′-bipyridine). Various carbonyl compounds having the general formula R1CH=CHCRO [where R1, R = C6H5, H; p-MeO-C6H4-,C6H4; p-CH3-C6H4, C6H5; (m-OMe-)(p-OMe-)C6H3, C6H5; C6H5, (CH3)2CH-; CH3, H; W-Br-C6H4-, C6H5] are reduced to corresponding allylicalcohol [R1CH=CHCRHOH] at 25°C within half an hour. During these reductions the double bond is partially reduced to give saturated alcohols as minor products having the molecular formula R1CH2CH2CRHOH. The reduction of trans-3-phenyl-2-propenal with NaBH4 and catalytic amounts of Ni(bpy)Cl2 in solvents containing active deuterium (D2O, CD3OD), leads to the partial incorporation of deuterium at the α and γ positions to give C-D bonded alcohols.
- Handique, Jyotirekha G.,Purkayashtha, Arup,Baruah, Jubaraj B.
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- A ONE-STEP CONVERSION OF ESTERS TO SECONDARY ALCOHOLS WITH LiBH4-RMgX
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A one-pot synthesis of secondary alcohols from esters and LiBH4-RMgX is described.
- Comins, Daniel L.,Herrick, James J.
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p. 1321 - 1324
(2007/10/02)
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