- Metal-free cascade boron–heteroatom addition and alkylation with diazo compounds
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Transition metal-catalyzed carbene transfer reaction is one of the most notable advances for C?C bond formation reactionsduring the past decade, which has been widely employed in the preparation of C3-substituted indoles. Here, we described an efficient e
- Lv, Jiahang,Zhao, Binlin,Han, Ying,Yuan, Yu,Shi, Zhuangzhi
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supporting information
p. 691 - 694
(2020/07/13)
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- Iron(II)-Based Metalloradical Activation: Switch from Traditional Click Chemistry to Denitrogenative Annulation
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A unique concept for the intermolecular denitrogenative annulation of 1,2,3,4-tetrazoles and alkynes was discovered by using a catalytic amount of Fe(TPP)Cl and Zn dust. The reaction precludes the traditional, more favored click reaction between an organic azide and alkynes, and instead proceeds by an unprecedented metalloradical activation. The method is anticipated to advance access to the construction of important basic nitrogen heterocycles, which will in turn enable discoveries of new drug candidates.
- Roy, Satyajit,Khatua, Hillol,Das, Sandip Kumar,Chattopadhyay, Buddhadeb
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supporting information
p. 11439 - 11443
(2019/07/17)
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- Boron Trichloride-Mediated Synthesis of Indoles via the Aminoboration of Alkynes
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We describe an efficient catalyst- and metal-free aminoboration of alkynes to 3-borylated indoles using one of the least expensive boron sources, BCl3. The major dichloro(indolyl)borane products can be used for the in situ construction of usefu
- Lv, Jiahang,Zhao, Binlin,Liu, Li,Han, Ying,Yuan, Yu,Shi, Zhuangzhi
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supporting information
p. 4054 - 4059
(2018/09/25)
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- Gold-Catalyzed Intermolecular Ynamide Amination-Initiated Aza-Nazarov Cyclization: Access to Functionalized 2-Aminopyrroles
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A novel gold-catalyzed intermolecular ynamide amination-initiated aza-Nazarov cyclization has been developed, allowing the facile and efficient synthesis of various 2-aminopyrroles in moderate to good yields. Furthermore, a mechanistic rationale for this
- Shu, Chao,Wang, Yong-Heng,Shen, Cang-Hai,Ruan, Peng-Peng,Lu, Xin,Ye, Long-Wu
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supporting information
p. 3254 - 3257
(2016/07/13)
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- Titanium-Promoted Cross-Coupling for the Selective Synthesis of Polysubstituted, Conjugated Amides
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α,β-Unsaturated amides are important building blocks and are key structural elements in a number of biologically active natural products. Despite their importance and prevalence, few methods exist to prepare conjugated amides directly and modularly. To address this gap, a titanium-promoted coupling of alkynes and isocyanates has been developed. The method is highly stereoselective, producing only the E isomer with good chemoselectivity and regioselectivity (>95/5), for unsymmetrical internal alkynes that contain a steric bias. The reactive titanacyclopentene intermediate formed from the coupling of the alkyne and isocyanate was additionally reacted with various electrophiles to access tetrasubstituted enamides.
- Chenniappan, Vinoth Kumar,Rahaim, Ronald J.
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supporting information
p. 5090 - 5093
(2016/10/14)
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- Palladium-catalyzed difunctionalization of internal alkynes via highly regioselective 6- endo cyclization and alkenylation of enynoates: Synthesis of multisubstituted pyrones
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An efficient Pd(II)-catalyzed difunctionalization reaction of internal alkynes is reported. In this reaction, various enynoates and electron-deficient alkenes were used for the syntheses of useful highly substituted pyrone derivatives via a 6-endo cycliza
- Tian, Pan-Pan,Cai, Sai-Hu,Liang, Qiu-Ju,Zhou, Xing-Yi,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 1636 - 1639
(2015/04/14)
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- Tandem catalytic C(sp3)-H amination/sila-sonogashira-hagihara coupling reactions with iodine reagents
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A new tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations. I(003) is a double agent: A tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process affords complex building blocks with high yields, and demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations.
- Buendia, Julien,Darses, Benjamin,Dauban, Philippe
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supporting information
p. 5697 - 5701
(2015/06/16)
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- 1,2,3-Triazole: Unique ligand in promoting iron-catalyzed propargyl alcohol dehydration
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A 1,2,3-traizole-promoted iron(III)-catalyzed propargyl alcohol dehydration was developed for the synthesis of conjugated enynes. The desired conjugated enynes were prepared in good to excellent yields (up to 95%) with a large substrate scope and excellen
- Yan, Wuming,Ye, Xiaohan,Akhmedov, Novruz G.,Petersen, Jeffrey L.,Shi, Xiaodong
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supporting information; experimental part
p. 2358 - 2361
(2012/06/18)
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- The vinyl moiety as a handle for regiocontrol in the preparation of unsymmetrical 2,3-aliphatic-substituted indoles and pyrroles
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Rho-Rho-Rho your boat: A rhodium catalyst effects the regioselective oxidative coupling of enynes with N-aryl ureas (X=NR2) and N-vinylacetamides (X=C(O)Me), affording the corresponding 2-alkenylindoles and 2-alkenylpyrroles in good yield. Simple hydrogenation delivers the C2/C3-aliphatic-substituted indole or pyrrole (see scheme).
- Huestis, Malcolm P.,Chan, Lina,Stuart, David R.,Fagnou, Keith
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supporting information; experimental part
p. 1338 - 1341
(2011/04/21)
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- Cp*Li as a base: application to palladium-catalyzed cross-coupling reaction of aryl-X or alkenyl-X (X=I, Br, OTf, ONf) with terminal acetylenes
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The reaction of aryl-X or alkenyl-X (X=I, Br, OTf, ONf) with terminal acetylenes in the presence of a catalytic amount of Pd(OAc)2 provided the alkynylated products in good yields by using Cp*Li (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) as a base.
- Uemura, Minoru,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1829 - 1833
(2008/09/18)
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- Zinc-catalyzed silylation of terminal alkynes
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(Chemical Equation Presented) A rapid and high-yielding silylation of terminal alkynes employing TMSOTf and catalytic quantities of Zn(OTf) 2 has been developed. The reaction works well for a variety of substrates including reactive esters. Fifteen examples with yields of >90% are reported.
- Rahaim Jr., Ronald J.,Shaw, Jared T.
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p. 2912 - 2915
(2008/09/19)
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- Palladium-catalyzed diastereoselective coupling of propargylic oxiranes with terminal alkynes
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A diastereoselective coupling of propargylic oxiranes with terminal alkynes has been developed with use of a palladium catalyst. The stereochemistries of the resulting 4-alkynyl-substituted 2,3-allenols have been altered depending on the palladium catalyst. An optically active antf-substituted aliene was synthesized from the reaction of an enantiomerically enriched propargylic oxirane without loss of chirality.
- Yoshida, Masahiro,Hayashi, Maiko,Shishido, Kozo
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p. 1643 - 1646
(2008/02/02)
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- Exploring skeletal diversity via ring contraction of glycal-derived scaffolds
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(Chemical Equation Presented) Aryl ether C-glycoside scaffolds have been prepared from tri-O-acetyl-D-glucal by C-glycosylation followed by allylic substitution with phenols mediated by Pd(0). The aryl ethers were subjected to either [3,3]-sigmatropic rea
- Yeager, Adam R.,Min, Geanna K.,Porco Jr., John A.,Schaus, Scott E.
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p. 5065 - 5068
(2007/10/03)
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- Rhodium-catalyzed regio- and enantioselective intermolecular [4+2] carbocyclization of 4-alkynals with N,N-dialkyl acrylamides
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(Chemical Equation Presented) Selective rings: A cationic Rh I-(R,R)-walphos complex catalyzes a highly regio-and enantioselective intermolecular [4+2] carbocyclization of 4-alkynals with N,N-dialkyl acrylamides to afford enantioenriched cyclohexanones (see scheme; cod = cycloocta-1,5-diene). This new route is attractive in view of the one-step access to 4-alkynals from commercially available reagents.
- Tanaka, Ken,Hagiwara, Yuji,Noguchi, Keiichi
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p. 7260 - 7263
(2007/10/03)
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- Generation of cycloalkylidene carbenes via exo-type cyclization of alkynyllithiums bearing remote leaving group
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The reaction of 5-hexynyl rosylate (3a) with alkynyllithium (RC≡CLi; R = Ph, TMS) gives enynes 5 and 6. The reaction proceeds through a mechanism involving a novel exo-type cyclization of 6-lithio-5-hexynyl tosylate to form cyclopentylidene carbene. Enyne 6 is produced by the addition of RC≡CLi to the carbene, whereas rearrangement of the carbene to cyclohexyne followed by carbolithiation with RC≡CLi gives enyne 5. The formation of cyclopentylidene carbene and cyclohexyne as intermediates is clearly demonstrated by trapping experiments with cyclohexene (and triethylsilane) and with 1,3- diphenylisobenzofuran, respectively. Alkynyllithiums derived from 3-butynyl and 6-heptynyl p-fluorobenzenesulfonates (19a,b) undergo a similar exo-type cyclization to give cyclopropylidene and cyclohexylidene carbenes, respectively.
- Harada, Toshiro,Iwazaki, Katsuhiro,Otani, Takeshi,Oku, Akira
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p. 9007 - 9012
(2007/10/03)
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- Diastereoselective syn or anti opening of propargylic epoxides. Synthesis of α-allenic alcohols
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Propargylic epoxides easily react with Grignard reagents and catalytic amounts of copper(I) salt to afford α-allenic alcohols. The reaction is highly diastereoselective and its stereochemical outcome (syn or anti isomer) can be fully controlled. The syn d
- Alexakis,Marek,Mangeney,Normant
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p. 1677 - 1696
(2007/10/02)
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- Vinyl Cations, 37. Rearrangement of Cyclic Homopropargyl Sulfonates to Condensed Cyclobutanones and Cyclopropyl Ketones
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Cyclic homopropargyl sulfonates 8 (tosylates, triflates, nonaflates, and damsylates) are prepared and solvolysed.The resulting rearrangement reactions are studied with respect to the properties of the solvents used, leaving groups, the substituent on the triple bond, and with respect to the ring size of the sulfonates 8.
- Hanack, Michael,Schuhmacher, Werner,Kunzmann, Erich
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p. 1467 - 1487
(2007/10/02)
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