- Phosphorous acid promoted isomerization of propargyl alcohols to α,β-unsaturated carbonyl compounds
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A metal-free and two-phase protocol for the Meyer-Schuster isomerization of propargyl alcohols to the corresponding α,β-unsaturated carbonyl compounds has been achieved in the presence of stoichiometric phosphorous acid aqueous solution, which produces the desired products in high yields with excellent stereoselectivity. Compared with the traditional methods, the procedure features broad scope of the substrates, mild conditions, and easy separation, providing an appealing alternative to the Meyer-Schuster reaction.
- Gan, Xiaotang,Fu, Zuqi,Liu,Yan, Yani,Chen, Chao,Zhou, Yongbo,Dong, Jianyu
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supporting information
(2019/07/12)
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- Palladium-catalyzed [3+2] annulation of allenyl carbinol acetates with C,N-cyclic azomethine imines
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In this paper, a palladium-catalyzed [3+2] annulation of allenyl carbinol acetates with azomethine imines has successfully been developed under mild reaction conditions, affording biologically interesting tetrahydropyrazoloisoquinoline derivatives in high to excellent yields and with excellent stereoselectivity. The reaction follows a tandem [3+2] cycloaddition/allylation/elimination of AcOH pathway. Allenyl carbinol acetates also reacted well with in situ generated azomethine imine under cocatalysis of Ag(i)/Pd(0) catalysts in a similar reaction pathway.
- Mao, Biming,Zhang, Junya,Xu, Yi,Yan, Zhengyang,Wang, Wei,Wu, Yongjun,Sun, Changqing,Zheng, Bing,Guo, Hongchao
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supporting information
p. 12841 - 12844
(2019/11/05)
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- A novel synthesis of N-hydroxy-3-aroylindoles and 3-aroylindoles
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A straightforward indole synthesis via annulation of C-nitrosoaromatics with conjugated terminal alkynones was realised achieving a simple, highly regioselective, atom- and step economical access to 3-aroylindoles in moderate to good yields. Further functionalizations of indole scaffolds were investigated and an easy way to JWH-018, a synthetic cannabinoid, was achieved.
- Ieronimo, Gabriella,Palmisano, Giovanni,Maspero, Angelo,Marzorati, Alessandro,Scapinello, Luca,Masciocchi, Norberto,Cravotto, Giancarlo,Barge, Alessandro,Simonetti, Marco,Ameta, Keshav Lalit,Nicholas, Kenneth M.,Penoni, Andrea
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supporting information
p. 6853 - 6859
(2018/10/20)
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- Chiral silver phosphate-catalyzed cycloisomeric kinetic resolution of α-allenic alcohols
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A kinetic resolution of α-allenic alcohols is realized through chiral silver phosphate-catalyzed cycloisomerization with high stereoselectivity (selectivity factor up to 189) and tolerance of a variety of functional groups. A mechanistic model is proposed to interpret the origin of the high stereoselectivity and broad substrate scope.
- Wang, Yan,Zheng, Kuan,Hong, Ran
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supporting information; scheme or table
p. 4096 - 4099
(2012/04/10)
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- Gold-catalyzed regioselective hydration of propargyl acetates assisted by a neighboring carbonyl group: Access to α-acyloxy methyl ketones and synthesis of (±)-actinopolymorphol B
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A general atom-economical approach for the synthesis of α-acyloxy methyl ketone is demonstrated through regioselective hydration of a wide range of propargyl acetates. Readily available catalyst comprising of 1% Ph 3PAuCl and 1% AgSbF6 in dioxane-H2O efficiently hydrolyzes the terminal alkynes of the propargyl acetate in the absence of acid promoters at ambient temperature within a short time. Effective regioselective hydration is facilitated by the neighboring carbonyl group as demonstrated through 18O-labeling study. Compatibility of functional moieties and tolerance to various acid-labile protecting groups are observed. The catalytic condition is also suitable to perform hydration of TMS-substituted propargyl acetates, even though it requires prolonged reaction time for completion. Stereointegrity of the propargylic acetate is preserved during the hydration. The robustness of the system is successfully demonstrated through gram scale preparation of the product in nearly quantitative yield. The common α-acyloxy methyl ketone is transformed to 1,2-diol and 1,2-amino alcohol derivatives. Synthesis of actinopolymorphol B is achieved for the first time involving hydration of the propargyl acetate as the key step.
- Ghosh, Nayan,Nayak, Sanatan,Sahoo, Akhila K.
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supporting information; experimental part
p. 500 - 511
(2011/04/17)
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- Efficient synthesis of 3-chloromethyl-2(5H)-furanones and 3-chloromethyl- 5,6-dihydropyran-2-ones via the PdCl2-catalyzed chlorocyclocarbonylation of 2,3- or 3,4-allenols
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(Chemical Equation Presented) A mild and efficient methodology involving PdCl2-catalyzed chlorocyclocarbonylation of 2,3- or 3,4-allenols with CuCl2 for the synthesis of 3-chloromethyl-2(5H)-furanones and 3-chloromethyl-5,6-dihydropyran-2-ones was developed. This reaction proceeded in a highly regioselective manner, i.e., the chlorine atom was introduced to the terminal position of the allene moiety while the lactone linkage was formed between the center carbon atom of the allene moiety and the hydroxyl oxygen, which was established by the X-ray single crystal diffraction study of γ-lactone 3p. The highly optically active 3-chloromethyl-2(5H)-furanones could be easily prepared from the readily available optically active 2,3-allenols. A mechanism for this reaction was proposed.
- Cheng, Xin,Jiang, Xuefeng,Yu, Yihua,Ma, Shengming
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scheme or table
p. 8960 - 8965
(2009/04/11)
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- Nematicidal pyrazoles
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Novel pyrazoles of formula (1) wherein R1 represents halogen, C1-6 alkyl, C1-5 haloalkyl, C2-6 alkoxy, C1-4 alkylthio, C2-5 alkenyloxy, C3-5 alkynyloxy, C2-6 (total carbon number) alkoxyalkyl, C2-6 (total carbon number) alkylthioalkyl, C1-5 haloalkoxy, C2-6 (total carbon number) alkoxyalkoxy, hydroxy or optionally substituted phenyl, R2 represents hydrogen, halogen, C1-5 alkyl, C2-6 (total carbon number) alkoxyalkyl, C2-6 (total carbon number) alkylthioalkyl, C2-6 (total carbon number) alkylsulfinylalkyl, C2-6 (total carbon number alkylsulfonylalkyl or C1-5 haloalkyl, R3 represents hydrogen, C1-5 alkyl, —COR4, COOR5, CH(OR6)2 or CH2Si(R7)3, R4 represents C1-10 alkyl, C1-6 haloalkyl, C2-6 alkenyl, optionally substituted C3-6 cycloalkyl, C2-6 (total carbon number) alkoxyalkyl, C2-6 (total carbon number alkylthioalkyl, optionally substituted phenyl, C1-6 haloalkyl, alkylamino, di-(C1-6 alkyl)amino or optionally substituted phenylamino, R5 represents C1-7 alkyl, R6 and R7 represent C1-6 alkyl, and n is 1, 2 or 3, and when n is 2 or 3, the corresponding number (n) of R1 radicals may be the same or different, processes for preparing these compounds and their use as nematicides and anthelmintics.
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- Stereoselective alkynylation of chiral benzaldehyde chromium tricarbonyl complexes. Synthesis of optically active alkynyl alcohols
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Addition of lithium acetylides and ethynyl magnesium bromide to chiral ortho substituted benzaldehyde tricarbonylchromium complexes 1-3 gives alkynyl alcohols 4-7 in good yields and with complete stereoselection.
- Baldoli, Clara,Del Buttero, Paola,Licandro, Emanuela,Maiorana, Stefano,Papagni, Antonio,Torchio, Maurizio
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p. 7943 - 7946
(2007/10/02)
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