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Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
Kumaki, Wataru,Kinoshita, Hidenori,Miura, Katsukiyo
supporting information

(2022/03/07)

Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information
p. 16470 - 16485
(2021/10/20)

Phosphine Evaluation on a New Series of Heteroleptic Copper(I) Photocatalysts with dpa Ligand [Cu(dpa)(P,P)]BF4
Five new heteroleptic copper(I) complexes (C1-5) of the type [Cu(dpa)(P,P)]BF4 based on dipyridylamine (dpa) as N,N ligand and commercial diphosphines as P,P ancillary ligands have been synthesised through a simple methodology with high yields. All complexes were thoroughly characterised by spectroscopic and spectrometric techniques, as well by theoretical calculations. These showed Metal to Ligand Charge Transfer (MLCT) absorptions in the 300–370 nm region, and emission in the 450–520 nm region with quantum yields and lifetimes that depend on the nature of the P,P ligand. The photocatalytic performance of copper(I) complexes C1-5 was evaluated for their use as photoredox catalysts in ATRA reactions, decarboxylative coupling and an Appel-type reaction. The use of readily available dpa as N,N ligand constitutes an attractive alternative to the well-established phenanthroline ligands typically used in photocatalysis.
Henriquez, Marco A.,Engl, Sebastian,Jaque, Pablo,Gonzalez, Ivan A.,Natali, Mirco,Reiser, Oliver,Cabrera, Alan R.
supporting information
p. 4020 - 4029
(2021/09/09)

Ni-Catalyzed Formal Cross-Electrophile Coupling of Alcohols with Aryl Halides
Direct coupling of unactivated alcohols remains a challenge in current synthetic chemistry. We herein demonstrate a strategy building upon in situ halogenation/reductive coupling of alcohols with aryl halides to forge Csp2-Csp3 bonds. The combination of 2-chloro-3-ethylbenzo[d]oxazol-3-ium salt (CEBO) and TBAB as the mild bromination reagents enables rapid transformation of a wide range of alcohols to their bromide counterparts within one to 5 min in CH3CN and DMF, which is compatible with the Ni-catalyzed cross-electrophile coupling conditions in the presence of a chemical reductant. The present method is suitable for arylation of a myriad of structurally complex alcohols with no need for prepreparation of alkyl halides. More importantly, the mild and kinetically rapid bromination process has shown good selectivity in the bromination/arylation of symmetric diols and less sterically hindered hydroxyl groups in polyols, thus offering promise for selective functionalization of diols and polyols without laborious protecting/deprotecting operations. The practicality of this work is also evident in the arylation of a number of carbohydrates, drug compounds, and naturally occurring alcohols.
Lin, Quan,Ma, Guobin,Gong, Hegui
p. 14102 - 14109
(2021/11/20)

An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
p. 8042 - 8048
(2020/09/21)

Making Copper Photocatalysis Even More Robust and Economic: Photoredox Catalysis with [CuII(dmp)2Cl]Cl
The CuII complex [CuII(dmp)2Cl]Cl (dmp = 2,9-dimethyl-1,10-phenanthroline) is evaluated as an oxidation stable precursor for visible-light-mediated CuI-photoredox catalysis, being efficient and considerable more cost-effective compared to previously established copper(I) photocatalysts. Its performance and efficiency are demonstrated within a broad scope of atom transfer radical addition (ATRA) reactions, allowing the 1,2-difunctionalization of alkenes, as well as for decarboxylative coupling and an Appel reaction. Moreover, the utility of the complex is shown by various gram-scale functionalizations of styrene, thus suggesting [CuII(dmp)2Cl]Cl to be a low-priced alternative precatalyst for processes run on scale. Furthermore, this study provides UV/Vis evidence on the mechanism for the visible light activation of CuII complexes.
Engl, Sebastian,Reiser, Oliver
supporting information
p. 1523 - 1533
(2019/07/31)

1,3-Diphenyldisiloxane Enables Additive-Free Redox Recycling Reactions and Catalysis with Triphenylphosphine
The recently reported chemoselective reduction of phosphine oxides with 1,3-diphenyldisiloxane (DPDS) has opened up the possibility of additive-free phosphine oxide reductions in catalytic systems. Herein we disclose the use of this new reducing agent as an enabler of phosphorus redox recycling in Wittig, Staudinger, and alcohol substitution reactions. DPDS was successfully utilized in ambient-temperature additive-free redox recycling variants of the Wittig olefination, Appel halogenation, and Staudinger reduction. Triphenylphosphine-promoted catalytic recycling reactions were also facilitated by DPDS. Additive-free triphenylphosphine-promoted catalytic Staudinger reductions could even be performed at ambient temperature due to the rapid nature of phosphinimine reduction, for which we characterized kinetic and thermodynamic parameters. These results demonstrate the utility of DPDS as an excellent reducing agent for the development of phosphorus redox recycling reactions.
Buonomo, Joseph A.,Cole, Malcolm S.,Eiden, Carter G.,Aldrich, Courtney C.
p. 3583 - 3594
(2020/09/15)

Thiourea-Mediated Halogenation of Alcohols
The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
supporting information
p. 12901 - 12911
(2020/11/26)

Photochemical benzylic bromination in continuous flow using BrCCl3 and its application to telescoped p-methoxybenzyl protection
BrCCl3 represents a rarely used benzylic brominating reagent with complementary reactivity to other reagents. Its reactivity has been revisited in continuous flow, revealing compatibility with electron-rich aromatic substrates. This has brought about the development of a p-methoxybenzyl bromide generator for PMB protection, which was successfully demonstrated on a pharmaceutically relevant intermediate on 11 g scale, giving 91% yield and a PMB-Br space-time-yield of 1.27 kg L?1 h?1
Otake, Yuma,Williams, Jason D.,Rincón, Juan A.,De Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
supporting information
p. 1384 - 1388
(2019/02/14)

Synthesis method of p-chloromethyl styrene
The invention relates to a synthesis method of an organic intermediate, in particular, a synthesis method of p-chloromethyl styrene. According to the synthesis method, a phase-transfer catalytic method is adopted; p-chloromethyl-alpha-bromoethylbenzene and potassium hydroxide are taken as the raw materials; toluene is taken as the solvent; and a phase-transfer catalysis is added to synthesize p-chloromethyl styrene. The synthesis method has the advantages that the reactions are mild, the energy consumption is low, no high pressure or high temperature is needed during the reaction process, thereactants do not react with the solvent or the phase-transfer catalyst, the yield is increased, the side reactions are reduced, and a high quality product is obtained.
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Paragraph 0049-0050

(2019/11/25)

Synthesis of α-methylstilbenes using an aqueous Wittig methodology and application toward the development of potent human aromatase inhibitors
The development of aqueous Wittig methodology for the synthesis of α-methylstilbenes using tripropylphosphine-derived phosphonium salts is described. The Wittig olefination reaction was high yielding and allowed isolation of stilbenes by simple filtration and washing with water. The novel phosphonium salts employed were accessed via a highly efficient, regioselective addition of hydrogen bromide to styrenes. Application of the α-methylstilbenes toward the synthesis of a collection of stilbenoid-triazoles is reported and their inhibition of CYP450 19A1 (aromatase) investigated. The overall structure-activity profile provided additional evidence on the aryl halide-ketone bioisostere hypothesis and identified 6c as a potent inhibitor of aromatase in vitro (Ki = 8 nM).
Nielsen, Alexander J.,Raez-Villanueva, Sergio,Crankshaw, Denis J.,Holloway, Alison C.,McNulty, James
supporting information
p. 1395 - 1398
(2019/04/03)

1,2-Dibromotetrachloroethane: An efficient reagent for many transformations by modified Appel reaction
An efficient and facile method has been developed for the synthesis of alkyl bromides from various alcohols under mild conditions using a triphenylphosphine (PPh 3) /1,2-dibromotetrachloroethane (DBTCE) complex in excellent yields and very short time (5 min). This method can also be applied for the transformation of chiral alcohols to their corresponding bromides in very high enantiomeric excess. The PPh 3 /DBTCE complex is also successfully applied to ring-opening reactions of cyclic ethers in mild conditions. Esterification, amidation, and formation of acid anhydrides under very mild experimental conditions are also successfully accomplished by following a modification of the Appel reaction protocol in this work.
Essiz, Sel?uk,Da?tan, Arif
p. 150 - 156
(2019/05/16)

Nucleophilic Substitutions of Alcohols in High Levels of Catalytic Efficiency
A practical method for the nucleophilic substitution (SN) of alcohols furnishing alkyl chlorides, bromides, and iodides under stereochemical inversion in high catalytic efficacy is introduced. The fusion of diethylcyclopropenone as a simple Lewis base organocatalyst and benzoyl chloride as a reagent allows notable turnover numbers up to 100. Moreover, the use of plain acetyl chloride as a stoichiometric promotor in an invertive SN-type transformation is demonstrated for the first time. The operationally straightforward protocol exhibits high levels of stereoselectivity and scalability and tolerates a variety of functional groups.
Stach, Tanja,Dr?ger, Julia,Huy, Peter H.
supporting information
p. 2980 - 2983
(2018/05/28)

Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
supporting information
p. 4197 - 4204
(2018/09/25)

Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
p. 4729 - 4737
(2018/10/23)

Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
supporting information
p. 4933 - 4939
(2018/12/14)

Silica gel-mediated hydrohalogenation of unactivated alkenes using hydrohalogenic acids under organic solvent-free conditions
Silica gel-mediated hydrochlorination of unactivated alkenes using 35% hydrochloric acid under organic solvent-free conditions proceeded to give the corresponding chlorides in good yields. Hydrobromination or hydriodination using 47% hydrobromic acid or 55% hydriodic acid afforded the corresponding halides, respectively. Silica gel could be recycled five times without any significant loss of activities.
Tanemura, Kiyoshi
supporting information
p. 4293 - 4298
(2018/11/10)

Copper(II) complexes of a heterotopic N-heterocyclic carbene ligand: Preparation and catalytic application
Copper complexes containing a N-heterocylic carbene (NHC)/amidate/pyridine tridentate, 3-mesityl-1-(2-oxo-2-[{pyridin-2-ylmethyl}amino]ethyl)-imidazolin-2-ylidene (HL), were synthesized and characterized. By X-ray single crystal analysis, both Cu(L)(OAc) (3a) and Cu(L)Br (3b) show that the metal center is coordinated by a CNN-tridentate and a anionic donor in a slightly distorted square-planar geometry. These copper complexes are active as catalysts for oxidative bromination of dimethoxybenzene and styrene with the use of LiBr as the bromine source and oxygen as the terminal oxidant.
Aaron Lin, Shih-Chieh,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
p. 52 - 57
(2018/02/14)

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow
A copper-based photocatalyst, Cu(tmp)(BINAP)BF4, was found to be active in a photoredox Appel-type conversion of alcohols to bromides. The catalyst was identified from a screening of 50 complexes and promoted the transformation of primary and secondary alcohols to their corresponding bromides and carboxylic acids to their anhydrides. The protocol was also amendable and optimized under continuous flow conditions.
Minozzi, Clémentine,Grenier-Petel, Jean-Christophe,Parisien-Collette, Shawn,Collins, Shawn K.
supporting information
p. 2730 - 2736
(2018/11/21)

Ligand-free Iron(II)-Catalyzed N-Alkylation of Hindered Secondary Arylamines with Non-activated Secondary and Primary Alcohols via a Carbocationic Pathway
Secondary benzylic alcohols represent a challenging class of substrates for N-alkylation of amines. Herein, we describe an iron(II)-catalyzed eco-friendly protocol for N-alkylation of secondary arylamines with secondary benzyl alcohols through a carbocationic pathway instead of the known borrowing hydrogen transfer (BHT) approach. Transiently generated carbocations, produced from alcohols via self-condensation, were coupled with arylamines to provide highly functionalized amine products. The scope of this methodology involves N-alkylation of primary, secondary and heterocyclic amines with primary/secondary benzylic, allylic and heterocyclic alcohols, which are common key structures in numerous pharmaceuticals drugs. The method can also be easily adopted for the amination of various natural products. (Figure presented.).
Nayal, Onkar S.,Thakur, Maheshwar S.,Kumar, Manoranjan,Kumar, Neeraj,Maurya, Sushil K.
supporting information
p. 730 - 737
(2017/12/26)

Electrophile-Directed Diastereoselective Oxonitrile Alkylations
Diastereoselective alkylation of prochiral oxonitrile dianions with secondary alkyl halides efficiently installs two contiguous stereogenic centers. The confluence of nucleophilic trajectory and the electrophile chirality causes distinct steric differences that allow efficient discrimination for one of the six possible conformers. Numerous oxonitrile-derived dianions efficiently displace secondary alkyl halides propagating the electrophile chirality to efficiently install two contiguous tertiary centers. The prevalence of chiral, secondary electrophiles makes the interdigitated alkylation of chiral electrophiles a particularly attractive route because the resulting oxonitriles are readily transformed into bioactive heterocycles.
Chepyshev, Sergiy V.,Pitta, Bhaskar Reddy,Vangala, Saidi Reddy,Lujan-Montelongo, J. Armando,Steward, Omar W.,Fleming, Fraser F.
supporting information
p. 2850 - 2853
(2018/02/09)

HBr–DMPU: The First Aprotic Organic Solution of Hydrogen Bromide
HBr and DMPU (1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone) form a room-temperature-stable complex that provides a mild, effective, and selective hydrobrominating reagent toward alkynes, alkenes, and allenes. HBr–DMPU could also replace other halogenating reagents in the halo-Prins reaction, ether cleavage, and deoxy-bromination reactions.
Li, Zhou,Ebule, Rene,Kostyo, Jessica,Hammond, Gerald B.,Xu, Bo
supporting information
p. 12739 - 12743
(2017/09/25)

TRICYCLIC COMPOUNDS
Provided herein are compounds and pharmaceutical compositions comprising said compounds that are useful for treating cancers or congenital diseases. Specific cancers and congenital disease includes those that are mediated by YAP/TAZ.
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Paragraph 00258

(2017/08/01)

PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00169; 00180

(2017/07/28)

Exploring the Reducing Ability of Organic Dye (Acr+-Mes) for Fluorination and Oxidation of Benzylic C(sp3)-H Bonds under Visible Light Irradiation
The excellent oxidizing capability of acridinium-based organic dye (Acr+-Mes) is fully studied in photoredox catalysis. However, its reducing ability is always considered weak for organic transformation. The reducing ability of Acr+-Mes is developed by Selectfluor to achieve effective fluorination and oxidation of benzylic C(sp3)-H bonds under visible light irradiation, which is not available for the direct use of oxidizing ability of excited Acr+-Mes. Mechanistic insights provided strong evidence for the oxidative quenching of Acr+-Mes.
Xiang, Ming,Xin, Zhi-Kun,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
supporting information
p. 3009 - 3012
(2017/06/07)

Catalytic Carbocation Generation Enabled by the Mesolytic Cleavage of Alkoxyamine Radical Cations
A new catalytic method is described to access carbocation intermediates via the mesolytic cleavage of alkoxyamine radical cations. In this process, electron transfer between an excited state oxidant and a TEMPO-derived alkoxyamine substrate gives rise to a radical cation with a remarkably weak C?O bond. Spontaneous scission results in the formation of the stable nitroxyl radical TEMPO.as well as a reactive carbocation intermediate that can be intercepted by a wide range of nucleophiles. Notably, this process occurs under neutral conditions and at comparatively mild potentials, enabling catalytic cation generation in the presence of both acid sensitive and easily oxidized nucleophilic partners.
Zhu, Qilei,Gentry, Emily C.,Knowles, Robert R.
p. 9969 - 9973
(2016/08/16)

Visible-light-mediated benzylic sp3 C-H bond functionalization to C-Br or C-N bond
A visible-light-promoted functionalization of unactivated benzylic sp3 C-H bonds was developed. Ethylbenzene derivatives were converted to the corresponding benzyl bromides or afforded benzylamine derivatives in a one-pot manner under visible light photoredox conditions.
Hou, Tianyuan,Lu, Ping,Li, Pixu
supporting information
p. 2273 - 2276
(2016/05/10)

Method for preparing 6-(1-phenyl-ethyl)-pyrrolo[3,4-b]pyridine-5,7-dione
The invention more specifically relates to a method for preparing 6-(1-phenyl-ethyl)-pyrrolo[3,4-b]pyridine-5,7-dione. The preparation method comprises the following steps: 5H-pyrrolo[3,4-b]pyridine-5,7(6H)-dione is generated from 2,3-dipicolinic acid and urea, ethylbenzene and hydrogen halide are reacted in order to generate (1-haloethyl)benzene, (1-haloethyl)benzene and 2,3-dipicolinic acid are generated into a crude product, and finally a target compound is obtained by chiral separation. The method is advantageous in that the synthesis technology has the advantages of mild reaction condition, short reaction time, high yield without generation of harmful refuses, simple post-treatment, recycling of 1,2-dichloroethane solvent which is separated from the reaction process, and easy industrialization.
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Paragraph 0016

(2017/05/26)

Scalable anti-Markovnikov hydrobromination of aliphatic and aromatic olefins
To improve access to a key synthetic intermediate we targeted a direct hydrobromination-Negishi route. Unsurprisingly, the anti-Markovnikov addition of HBr to estragole in the presence of AIBN proved successful. However, even in the absence of an added initiator, anti-Markovnikov addition was observed. Re-examination of early reports revealed that selective Markovnikov addition, often simply termed "normal" addition, is not always observed with HBr unless air is excluded, leading to the rediscovery of a reproducible and scalable initiator-free protocol.
Galli, Marzia,Fletcher, Catherine J.,Del Pozo, Marc,Goldup, Stephen M.
supporting information
p. 5622 - 5626
(2016/07/06)

Direct halogenation of alcohols with halosilanes under catalyst- and organic solvent-free reaction conditions
A chemoselective method for the direct halogenation of different types of alcohols with halosilanes under catalyst- and solvent-free reaction conditions (SFRC) is reported. Various primary, secondary and tertiary benzyl alcohols and tertiary alkyl alcohols were directly transformed to the corresponding benzyl and alkyl halides, respectively, using chlorotrimethylsilane (TMSCl) and bromotrimethylsilane (TMSBr).
Ajvazi, Njomza,Stavber, Stojan
supporting information
p. 2430 - 2433
(2016/05/19)

An efficient and selective method for the iodination and bromination of alcohols under mild conditions
A straightforward and effective procedure for the conversion of a variety of alcohols into the corresponding alkyl iodides and bromides is described using KX/P2O5 (X = I, Br). The reactions were easily carried out in acetonitrile under mild conditions. Using this method, the selective conversion of benzylic alcohols in the presence of aliphatic alcohols was achieved.
Khazdooz, Leila,Zarei, Amin,Aghaei, Hamidreza,Azizi, Ghobad,Gheisari, Mohammad Mehdi
p. 168 - 171
(2015/12/30)

A Novel Internet-Based Reaction Monitoring, Control and Autonomous Self-Optimization Platform for Chemical Synthesis
We have developed a modular software system that enables researchers to monitor and control chemical reactions via the Internet, using any device from any location in the world. It facilitates the automation of synthetic procedures and is able to autonomously self-optimize reaction parameters to find the best conditions meeting customizable, multicomponent optimization functions. In this report, we demonstrate its utility as applied to reaction automation to maximize the output from a fixed volume of catalyst. We also showcase its ability to optimize a three-dimensional heterogeneous catalytic reaction and a five-dimensional Appel reaction against various target functions.
Fitzpatrick, Daniel E.,Battilocchio, Claudio,Ley, Steven V.
supporting information
p. 386 - 394
(2016/03/04)

METHOD OF CONVERTING ALCOHOL TO HALIDE
The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
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Page/Page column 182; 183; 184

(2017/01/02)

Microreactor-mediated benzylic bromination in concentrated solar radiation
Sunlight-induced bromination of benzylic compounds was conducted in a capillary microreactor, resulting in mono-brominated compounds with yields of up to 94%. These reactions can be considered to be eco-friendly since they were carried out without an artificial light source or additional temperature control. In addition, up to 257.9mmol could be produced daily using cost-effective molecular bromine, which leads to potential improvement of industrial processes.
Kim, Young Joon,Jeong, Myung Jin,Kim, Ji Eun,In, Insik,Park, Chan Pil
p. 1653 - 1656
(2015/11/10)

Tribromoisocyanuric acid as a green reagent for benzylic bromination of alkylarenes
The reaction of diverse alkylarenes with tribromoisocyanuric acid (0.34 mol equiv) in reflux EtOAc in the absence of any catalysts or light irradiation produced the corresponding benzyl bromides in 53-88% yield.
De Almeida, Leonardo S.,Esteves, Pierre M.,De Mattos, Marcio C.S.
p. 6843 - 6845
(2015/11/27)

NOVEL COMPOUNDS AS HISTONE DEACETYLASE 6 INHIBITORS AND PHARMACEUTICAL COMPOSITIONS COMPRISING THE SAME
The present invention relates to novel compounds having histone deacetylase 6 (HDAC6) inhibitory activity, isomers thereof, or pharmaceutically acceptable salts thereof, the use thereof for the preparation of therapeutic medicaments, pharmaceutical compositions comprising the same, a method of treating disease using the composition, and methods for preparing the novel compounds. The novel compounds according to the present invention have histone deacetylase 6 (HDAC6) inhibitory activity, and are effective for the prevention or treatment of HDAC6-associated diseases, including cancer, inflammatory diseases, autoimmune diseases, neurological diseases and neurodegenerative disorders.
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Paragraph 907; 908

(2015/10/05)

On the ionizing properties of supercritical carbon dioxide: Uncatalyzed electrophilic bromination of aromatics
Supercritical carbon dioxide (scCO2), a solvent with a zero dipole moment, low dielectric constant, and no hydrogen bonding behavior, is a suitable medium to perform the uncatalyzed electrophilic bromination of weakly activated aromatics with no interference of radical pathways. The ability of scCO2 to promote these reactions matches those of strongly ionizing solvents such as aqueous acetic and trifluoroacetic acids. Conversely, carbon tetrachloride, with similar polarity parameters to scCO2, leads exclusively to side chain functionalization. The strong quadrupole moment, and the acidic, but non basic, Lewis character of carbon dioxide, are proposed as key factors for the singular performance of scCO2 in reactions involving highly polar and ionic intermediates.
Delgado-Abad, Thais,Martnez-Ferrer, Jaime,Reig-Lpez, Javier,Mello, Rossella,Acerete, Rafael,Asensio, Gregorio,Gonzlez-Nez, Mara Elena
p. 51016 - 51021
(2015/01/16)

A scalable procedure for light-induced benzylic brominations in continuous flow
A continuous-flow protocol for the bromination of benzylic compounds with N-bromosuccinimide (NBS) is presented. The radical reactions were activated with a readily available household compact fluorescent lamp (CFL) using a simple flow reactor design based on transparent fluorinated ethylene polymer (FEP) tubing. All of the reactions were carried out using acetonitrile as the solvent, thus avoiding hazardous chlorinated solvents such as CCl4. For each substrate, only 1.05 equiv of NBS was necessary to fully transform the benzylic starting material into the corresponding bromide. The general character of the procedure was demonstrated by brominating a diverse set of 19 substrates containing different functional groups. Good to excellent isolated yields were obtained in all cases. The novel flow protocol can be readily scaled to multigram quantities by operating the reactor for longer time periods (throughput 30 mmol h-1), which is not easily possible in batch photochemical reactors. The bromination protocol can also be performed with equal efficiency in a larger flow reactor utilizing a more powerful lamp. For the bromination of phenylacetone as a model, a productivity of 180 mmol h -1 for the desired bromide was achieved.
Cantillo, David,De Frutos, Oscar,Rincon, Juan A.,Mateos, Carlos,Oliver Kappe
supporting information
p. 223 - 229
(2014/01/17)

Revisiting the bromination of c-h bonds with molecular bromine by using a photo-microflow system
The photobromination of C-H bonds by using molecular bromine was reinvestigated under microfluidic conditions. The continuous-flow method suppressed the production of dibrominated compounds and effectively produced the desired monobrominated products with high selectivity. Rapid bromination of benzylic substrates containing a photoaffinity azide group was achieved without any decomposition. Go with the (micro)flow: Photobromination of C-H bonds by using molecular bromine under microfluidic conditions has been investigated (see scheme). The continuous-flow method suppressed the production of dibrominated compounds and effectively produced the desired monobrominated compounds with high selectivity. Rapid bromination of benzylic substrates containing a photoaffinity azide group was achieved without any decomposition.
Manabe, Yoshiyuki,Kitawaki, Yuriko,Nagasaki, Masahiro,Fukase, Koichi,Matsubara, Hiroshi,Hino, Yoshiko,Fukuyama, Takahide,Ryu, Ilhyong
supporting information
p. 12750 - 12753
(2015/03/30)

Auto de-bromine-coupling reactions of 1-aryl-7-bromocycloheptenes
Auto de-bromine-coupling reactions of 1-aryl-7-bromocycloheptenes to a new series of [7-6-6] tricyclic system were described. A variety of substituents at the para-position of the phenyl were amenable to this transformation, including electron-donating groups and halides. The presence of electron-donating groups resulted in a more efficient reaction, with higher yields than the case of halides.
Lee, Gon-Ann,Lee, Hsin-Yi,Wang, Wen-Chieh,Cherng, Chih-Hwa
p. 2956 - 2961
(2014/04/17)

Rasta resin-triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions
Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as reagent precursors in a wide range of halogenation reactions. The rasta resin-triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form halogenated products in high yields after simple purification. The polymersupported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity.
Xia, Xuanshu,Toy, Patrick H.
supporting information
p. 1397 - 1405
(2014/07/22)

Inorganic micelles as efficient and recyclable micellar catalysts
An "inorganic micelle" structure that has a hydrophilic cavity and hydrophobic surface has been synthesized. The inorganic micelles possess large surface area and controllable hydrophobic/hydrophilic interface. It shows high catalytic efficiency and great recyclability in the bromination of alcohols. This work suggests that inorganic micelles may be suitable for selective organic syntheses as well as industrial applications and demonstrates the value of translating nanostructure design from organic to inorganic.
Zhang, Qiao,Shu, Xing-Zhong,Lucas, J. Matthew,Toste, F. Dean,Somorjai, Gabor A.,Alivisatos, A. Paul
p. 379 - 383
(2014/01/23)

Reactions of difluorocarbene with organozinc reagents
Reactions of difluorocarbene with benzyl and alkylzinc halides leading to fluorinated organozinc species have been described. The generated α-difluorinated organozinc reagents are reasonably stable in solution and can be quenched with external electrophiles (iodine, bromine, proton), affording compounds containing the CF2 fragment.
Levin, Vitalij V.,Zemtsov, Artem A.,Struchkova, Marina I.,Dilman, Alexander D.
p. 917 - 919
(2013/03/28)

Supercritical carbon dioxide: A promoter of carbon-halogen bond heterolysis
Amazing reaction medium: Supercritical carbon dioxide, with zero dipole moment, lower dielectric constant than pentane, and non-hydrogen-bonding behavior, ionizes carbon-halogen bonds, dissociates the resulting ion pairs, and escapes from capture by the carbocation intermediates at temperatures above 40 °C. These properties allow the observation of carbocation chemistry in the absence of acids.
Delgado-Abad, Thais,Martinez-Ferrer, Jaime,Caballero, Ana,Olmos, Andrea,Mello, Rossella,Gonzalez-Nunez, Maria Elena,Perez, Pedro J.,Asensio, Gregorio
supporting information
p. 13298 - 13301
(2014/01/06)

In situ generated Ph3P(OAc)2as a novel reagent for the efficient acetylation of alcohols and thiols at room temperature
Ph3P, Br2, and ammonium acetate are used for the in situ generation of Ph3P(OAc)2, which was characterized by different NMR techniques. The Ph3P(OAc)2generated was used as a novel and efficient reagent for the acetylation of alcohols and thiols in acetonitrile at room temperature under homogeneous conditions. This reaction was also performed under heterogeneous conditions using 1,3,2,4- diazadiphosphetidine as an easily prepared, stable, and heterogeneous P(III) compound.
Iranpoor, Nasser,Firouzabadi, Habib,Elham, Etemadi Davan
p. 1813 - 1816
(2013/04/24)

Synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters from arylmethyl azides via a domino process
A convenient synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters via a domino process is described. The synthesis employs arylmethyl azides as the precursor which undergoes an acid-promoted rearrangement to give an N-aryl iminium ion. Following the addition with ethyl 3-ethoxyacrylate, intramolecular electrophilic aromatic substitution, elimination and subsequent oxidation, the quinoline products were obtained in moderate to excellent yields.
Tummatorn, Jumreang,Thongsornkleeb, Charnsak,Ruchirawat, Somsak,Gettongsong, Tanita
supporting information
p. 1463 - 1467
(2013/05/08)

Synthesis of silica bromide as heterogeneous reagent and its application to conversion of alcohols to alkyl bromides
Silica bromide as heterogeneous reagent is prepared from the reaction of silica gel with PBr3 as a nonhydroscopic, filterable, cheap, and stable yellowish powder that can be stored for months. The results show that the silica bromide is a suitable and efficient reagent for conversion of alcohols to alkyl bromides under mild conditions at room temperature. The easy availability of this reagent makes this simple procedure attractive and a practical alternative to the existing methods.
Mohanazadeh, Farajollah,Sedrpoushan, Alireza,Zolfigol, Mohammad A.,Veisi, Hojat
p. 598 - 603,6
(2012/12/11)

Polyvinylpyrrolidone-bromine complex: An efficient polymeric reagent for selective preparation of benzyl bromides in the presence of hexamethyldisilane
Benzylic bromides were conveniently obtained in high yields via the reaction of the corresponding alcohols with crosslinked polyvinylpyrrolidone- bromine complex (PVPP-Br2)/hexamethyldisilane in chloroform at reflux condition. Selective conversion of benzyl alcohol to benzyl bromide in the presence of primary aliphatic alcohols, e.g. 2-phenylethanol was also achieved.
Mokhtary, Masoud,Lakouraj, Moslem M.
p. 305 - 309
(2012/10/29)

Catalytic enantioselective cross-couplings of secondary alkyl electrophiles with secondary alkylmetal nucleophiles: Negishi reactions of racemic benzylic bromides with achiral alkylzinc reagents
We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however, a new, readily available bidentate isoquinoline-oxazoline ligand furnishes excellent ee's and good yields. The use of acyclic alkylzinc reagents as coupling partners led to the discovery of a highly unusual isomerization that generates a significant quantity of a branched cross-coupling product from an unbranched nucleophile.
Binder, Joerg T.,Cordier, Christopher J.,Fu, Gregory C.
supporting information
p. 17003 - 17006,4
(2012/12/11)

Catalytic enantioselective cross-couplings of secondary alkyl electrophiles with secondary alkylmetal nucleophiles: Negishi reactions of racemic benzylic bromides with achiral alkylzinc reagents
We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however, a new, readily available bidentate isoquinoline-oxazoline ligand furnishes excellent ee's and good yields. The use of acyclic alkylzinc reagents as coupling partners led to the discovery of a highly unusual isomerization that generates a significant quantity of a branched cross-coupling product from an unbranched nucleophile.
Binder, Joerg T.,Cordier, Christopher J.,Fu, Gregory C.
supporting information
p. 17003 - 17006
(2013/01/15)