- Ynoate-Initiated Selective C-N Esterification of Tertiary Amines under Transition-Metal and Oxidant-Free Conditions
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An efficient and selective method for metal-and oxidant-free deaminated esterification of tertiary amines is presented. In this protocol, ynoates play a key role to activate the Csp 3-N bond through a process of in situ generation of zwitterionic salts. The transformations show that Csp 3-N bond in the zwitterionic species has a lower dissociation energy than Csp 2-N bond, leading to break preferentially and be trapped by carboxylic acids to generate the corresponding products in moderate to good yield.
- Sun, Feixiang,Feng, Huangdi,Huang, Liliang,Huang, Junhai
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supporting information
p. 713 - 717
(2021/01/14)
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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- Copper-Catalyzed Oxyalkynylation of C-S Bonds in Thiiranes and Thiethanes with Hypervalent Iodine Reagents
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We report the oxyalkynylation of thiiranes and thietanes using ethynylbenziodoxolone reagents (EBXs) to readily access functionalized building blocks bearing an alkynyl, a benzoate, and an iodide group. The reaction proceeds with high atom efficiency most
- Borrel, Julien,Pisella, Guillaume,Waser, Jerome
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supporting information
p. 422 - 427
(2020/01/31)
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- Metal-Free Synthesis of 4-Chloroisocoumarins by TMSCl-Catalyzed NCS-Induced Chlorinative Annulation of 2-Alkynylaryloate Esters
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4-Chloroisocoumarins can be conveniently prepared from 2-alkynylaryloate esters via the activation of alkynes by electrophilic chlorine, generated in situ from N-chlorosuccinimide (NCS) in the presence of 10 mol % trimethylsilyl chloride (TMSCl), which leads to 6-endo-dig-selective chlorinative annulation to give the desired products in moderate to quantitative yields. The procedure employs readily available reagents and can be conveniently carried out on a wide scope of substrates under mild conditions (0 °C to rt). Furthermore, the reaction is scalable for gram-scale preparation of 4-chloroisocoumarins. Additionally, 4-bromo- and 4-iodoisocoumarins can be prepared in moderate to good yields by replacing NCS with N-bromosuccinimide (NBS) and N-iodosuccinimide (NIS), respectively.
- Norseeda, Krissada,Chaisan, Nattawadee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Ruchirawat, Somsak
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p. 16222 - 16236
(2019/12/25)
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- Programmed twisting of phenylene-ethynylene linkages from aromatic stacking interactions
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Control over the conformation and packing of conjugated materials is an unsolved problem that prevents the rational design of organic optoelectronics, such as preventing self-quenching of luminescent molecules. Exacerbating this challenge is a general lack of widely applicable strategies for controlling packing with discrete, directional non-covalent interactions. Here, we present a series of conjugated molecules with diverse backbones of three or four arenes that feature pentafluorobenzyl ester substituents. Nearly all the compounds reveal intramolecular stacking interactions between the fluoroarene (ArF) side-chains and non-fluorinated arenes (ArH) in the middle of the chromophores; a twisted PE linkage accompanies each example of this intramolecular ArF-ArH stacking. Furthermore, these molecules can resist dramatic changes to emission upon transition from organic solution to thin film when ArF rings prevent interchromophore interactions. By broadening the structural space of conjugated backbones over which ArF-ArH stacking can twist PE linkages reliably and prevent self-quenching of solids with simple synthetic approaches, this work suggests fluorinated benzyl ester substituents adjacent to phenylene ethynylene linkages as supramolecular synthons for the crystal engineering of organic optoelectronic materials.
- Mullin, William J.,Pawle, Robert H.,Sharber, Seth A.,Müller, Peter,Thomas, Samuel W.
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p. 1198 - 1207
(2019/02/07)
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- Carboxylate-Assisted Oxidative Addition to Aminoalkyl PdII Complexes: C(sp3)?H Arylation of Alkylamines by Distinct PdII/PdIV Pathway
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Reported is the discovery of an approach to functionalize secondary alkylamines using 2-halobenzoic acids as aryl-transfer reagents. These reagents promote an unusually mild carboxylate-assisted oxidative addition to alkylamine-derived palladacycles. In the presence of AgI salts, a decarboxylative C(sp3)?C(sp2) bond reductive elimination leads to γ-aryl secondary alkylamines and renders the carboxylate motif a traceless directing group. Stoichiometric mechanistic studies were effectively translated to a Pd-catalyzed γ-C(sp3)?H arylation process for secondary alkylamines.
- Whitehurst, William G.,Blackwell, J. Henry,Hermann, Gary N.,Gaunt, Matthew J.
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supporting information
p. 9054 - 9059
(2019/06/04)
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- K2S2O8-promoted [2+2]-cycloaddition of benzyl-2-(3-hydroxypropynyl)-benzoates: A new route to polysubstituted cyclobutanes
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An efficient and convenient metal-free [2+2]-cycloaddition of benzyl-2-(3-hydroxypropynyl)-benzoates via allene processes has been developed, which provides impressive access to fused cyclobutanes from easily accessed π-components. This transformation involved the cleavage of two C–O bonds, the formations of two C–O bonds and two C–C bonds and showed some advantages, including mild conditions and wide substrate scope.
- Zhu, Hai-Tao,Tong, Xiao-Juan,Zhou, Ni-Ni,Yang, De-Suo,Fan, Ming-Jin
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supporting information
p. 5497 - 5500
(2016/11/19)
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- Transition metal free oxidative esterification of alcohols with toluene
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Using Bu4NI as the catalyst and tert-butyl hydroperoxide as the oxidant, direct esterification of alcohols with toluene derivatives was achieved. Mechanistic investigations indicate that the alcohols are sequentially oxidized to aldehydes, carboxylic acids, and then to benzyl esters. Bu 4N+ functions as a phasetransfer reagent and iodide catalyzes the reaction.
- Liu, Lianghui,Yun, Lin,Wang, Zikuan,Fu, Xuefeng,Yan, Chun-Hua
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supporting information
p. 5383 - 5386
(2013/09/12)
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- Straightforward reductive esterification of carbonyl compounds with carboxylic acids through tosylhydrazone intermediates
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The reaction of carboxylic acids with tosylhydrazones in basic media gives rise to the corresponding esters through an O-H insertion reaction in the in situ generated diazo compound. The process is operationally very simple, catalyst free, and very general with regard to the structure of both coupling partners. In particular, the esterification can be accomplished by employing tosylhydrazones derived from enolizable carbonyl compounds. Considering the ready availability of tosylhydrazones from carbonyl compounds, this reaction can be visualized as a reductive esterification of carbonyl compounds.
- Garcia-Munoz, Angel-Humberto,Tomas-Gamasa, Maria,Perez-Aguilar, M. Carmen,Cuevas-Yanez, Erick,Valdes, Carlos
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supporting information; experimental part
p. 3925 - 3928
(2012/08/28)
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- Nitromethane with IBX/TBAF as a nitrosating agent: Synthesis of nitrosamines from secondary or tertiary amines under mild conditions
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Aliphatic or aromatic N,N-disubstituted nitrosamine was generated in fair to excellent yield from the reaction of a secondary or tertiary amine with o-iodoxybenzoic acid (IBX) or o-iodosylbenzoic acid (IBA)/R4NX (X = halide) and nitromethane. The product yield was strongly influenced by both the halide of R4NX and iodanes. IBX gave a higher yield than IBA, while the halides follow F- > Cl- > Br- ~ I-. Nitrous acid formed in situ from nitromethane and IBX (or IBA)/halides is likely responsible for the observed reaction.
- Potturi, Hima K.,Gurung, Ras K.,Hou, Yuqing
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body text
p. 626 - 631
(2012/02/16)
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- Facile synthesis of 2-iodo-spiro[indene-1,1′-isobenzofuran]-3′- ones via iodine-promoted cascade cyclization
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A novel and efficient synthetic approach to substituted 2-iodo-spiro[indene-1,1′-isobenzofuran]-3′-ones has been developed via an iodine-promoted cascade cyclization of 2-(3-hydroxy-3,3-diarylprop-1-yn- 1-yl)benzoates. This sequential cascade process is concisely conducted at room temperature. Subsequent palladium-catalyzed Sonogashira, Suzuki, and Heck reactions of the resulting iodides proceed smoothly in good yields.
- Zhu, Hai-Tao,Dong, Xue,Wang, Li-Jing,Zhong, Mei-Jin,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 10748 - 10750,3
(2020/09/02)
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- Gold-catalyzed C-S bond formation from thiols
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ortho-Alkynylbenzoic acid alkyl esters act as alkylating agents of thiol derivatives with PPh3AuCl in combination with AgOTf in 1,2-dichloroethane at 80 °C. The corresponding sulfide compounds are obtained in good to excellent yields.
- Jean, Micka?l,Renault, Jacques,van de Weghe, Pierre,Asao, Naoki
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supporting information; experimental part
p. 378 - 381
(2010/03/24)
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- Formation of carbocycles by intramolecular conjugate displacement: Scopeand mechanistic insights
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A detailed study has been made of a method of ring closure categorized as an all-carbon intramolecular conjugate displacement (ICD). This reaction involves intramolecular addition of a carbanion, which is stabilized by at least one electron-withdrawing group, to a Michael acceptor which has a leaving group in an allylic position. The process formally resembles a combination of Michael addition and S N2' displacement. The overall result is formation of a ring with loss of the allylic leaving group and shift of the original double bond to a new location spanning the positions of the electron-withdrawing substituent of the Michael acceptor subunit and the original allylic leaving group. The starting materials are easily prepared by a selenium-based version of the Morita-Baylis-Hillman reaction. The cyclizations are transition metal free and occur under mild conditions, using DBU or Cs 2CO 3 inMeCN or THF. Acetate is a suitable leaving group and the electron-withd rawing substituent of the Michael acceptor unit can be CO 2R,SO 2Ph, or CN. Six- and seven-membered rings are formed effi ciently, and complex structures, such as those resembling the core of CP-225,917, are easily assembled. The products of these ICD reactions are themselves classical Michael acceptors. A range of mechanisms probably operates, depending on the structure of the starting material and the reaction conditions, but conclusive evidence for a stepwise mechanism was obtained in a suitably biased case, while other observations are compatible with a concerted process or a stepwise path involving a short-lived carbanion that evades capture by a proton source.
- Wang, Lihong,Prabhudas, Bodhuri,Clive, Derrick L. J.
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supporting information; experimental part
p. 6003 - 6012
(2009/09/25)
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- Prostaglandin analogs
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Thromboxane receptor antagonist activity is exhibited by compounds of the formula STR1 wherein: V is --(CH 2) m --, --O--, or STR2 but if V is --O--or STR3 R 3 and R 4 must complete an aromatic ring; W is --(CH 2) 2 --, --CH CH-- or phenylene;X is a single bond, --CH CH--, --(CH 2) n --, or --O--(CH 2) n --; or X is branched alkylene or --O--branched alkylene wherein W is linked to Y through a chain n carbon atoms long;Y is --CO 2 H, --CO 2 alkyl, --CO 2 alkali metal, --CH 2 OH, --CONHSO 2 R 5, --CONHR 6, or --CH 2 -5-tetrazolyl;Z is O or NH;R 3 and R 4 are each independently hydrogen or alkyl or R 3 and R 4 together complete a ring optionally substituted through a ring carbon with a halo, lower alkyl, phenyl, halo (lower alkyl), halophenyl, oxo or hydroxyl group; and the remaining symbols are as defined in the specification.
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- A CONVENIENT PREPARATION OF 1,2-DIACYLGLYCEROLS; o-IODOBENZOYL AS A PROTECTING GROUP
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The o-iodobenzoyl moiety is a useful 3-hydroxyl protecting group in the synthesis of 1,2-diacylglycerols; it can be removed by chlorination followed by mild basic hydrolysis.
- Moss, Robert A.,Scrimin, Paolo,Bhattacharya, Santanu,Chatterjee, Swati
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p. 5005 - 5008
(2007/10/02)
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