- Rh(iii)-catalyzed diastereoselective cascade annulation of enone-tethered cyclohexadienonesviaC(sp2)-H bond activation
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Herein, we report highly diastereoselective arylative cyclization of enone-tethered cyclohexadienonesviaRh(iii)-catalyzed C-H activation ofN-methoxybenzamides. This reaction proceeds through the formation of a five-membered rhodacycle followed by bis-Michael cascade annulation to access functionalized bicyclic scaffolds with four contiguous stereocenters with a broad substrate scope. These products have excellent functional handles, allowing further synthetic transformation to increase the structural complexity. Furthermore, mechanistic studies of arylative cyclization and a gram-scale experiment are also presented.
- Chegondi, Rambabu,Jadhav, Sandip B.,Maurya, Sundaram,Navaneetha, N.
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supporting information
p. 13598 - 13601
(2021/12/23)
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- Synthesis of Polysubstituted Pyridines via a One-Pot Metal-Free Strategy
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An efficient strategy for the one-pot synthesis of polysubstituted pyridines via a cascade reaction from aldehydes, phosphorus ylides, and propargyl azide is reported. The reaction sequence involves a Wittig reaction, a Staudinger reaction, an aza-Wittig reaction, a 6π-3-azatriene electrocyclization, and a 1,3-H shift. This protocol provides quick access to the polysubstituted pyridines from readily available substrates in good to excellent yields.
- Wei, Hongbo,Li, Yun,Xiao, Ke,Cheng, Bin,Wang, Huifei,Hu, Lin,Zhai, Hongbin
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supporting information
p. 5974 - 5977
(2016/01/09)
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- Synthesis and transformations of triphenylpropargylphosphonium bromide
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A method of the synthesis of triphenylpropargylphosphonium bromide is developed. Its isomerization and hydration in various solvents are studied, and reactions with secondary amines, triethylamine, and triphenylphosphine are carried out. It is established that secondary amines add to the intermediate allene isomer with subsequent migration of the formed double bond to the phosphorus atom. The reaction of triethylamine with triphenylpropargyl and triphenylethynyl bromides occurs similarly to alkaline hydrolysis involving attack of the amine on the phosphorus atom. Triphenylphosphine forms with triphenylpropargylphosphonium bromide a bis-salt with a terminal methylene group. Experimental evidence is obtained showing that for phosphoxazole derivatives to form from oximes derived from triphenyl(oxomethyl)phosphonium salts that latter should bear an aryl substituent at the keto group.
- Bagdasaryan,Pogosyan,Panosyan,Indzhikyan
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p. 1177 - 1183
(2008/12/22)
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- Diene-yne cyclisation reactions of 1-ethynyl-2-vinyl-3,4- dihydronaphthalenes and 1-ethynyl-2-vinylnaphthalenes
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The reaction of 1-ethynyl-2-vinyl-3,4-dihydronaphthalenes and 1-ethynyl-2-vinylnaphthalenes over RuCI2(p-cymene) PPh3 leads to 9,10-dihydrophenanthrenes and phenanthrenes in those cases where the ethynyl group in the substrates carries a terminal proton. When 1-phenylethynyl-2-vinyl-3,4-dihydronaphthalenes or 1-phenylethynyl-2- vinylnaphthalenes are reacted over Pt(PPh3)4, 1-methylene-1H-benz[e]-4,5-dihydroindenes and 1-methylene-1H-benz[e]indenes are formed.
- Watanabe, Masataka,Shiine, Kodai,Ldeta, Keiko,Matsumoto, Taisuke,Thiemann, Thies
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experimental part
p. 669 - 678
(2009/09/06)
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- A convenient method for the preparation of α-vinylfurans by phosphine-initiated reactions of various substituted enynes bearing a carbonyl group with aldehydes
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α-Vinylfurans were obtained by phosphine-initiated cyclization of various enynes bearing a carbonyl group at the ene end in the presence of various aldehydes, in moderate to high yields. The reaction may consist of 1,6-addition of phosphine to the enynes, ring closure, and Wittig reaction between the ylid resulting from cyclization and an aldehyde. Thus, various aldehydes were able to be used in the reaction. The reaction was influenced greatly by the substituents at the acetylene position (R1) and the α-position of the carbonyl group (R3).
- Kuroda, Hirofumi,Hanaki, Emi,Izawa, Hironori,Kano, Michiko,Itahashi, Hiromi
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p. 1913 - 1920
(2007/10/03)
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- Acetonyltriphenylphosphonium bromide in organic synthesis: A useful catalyst in the cyclotrimerization of aldehydes
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Acetonyltriphenylphosphonium bromide (ATPB) is a useful catalyst for the cyclotrimerization of the aliphatic aldehydes under solvent-free condition. The aldehydes tethered with a variety of functionality such as olefin, ether, ester, bromide, azide and diester could also be cyclotrimerized under the catalysis of ATPB.
- Hon, Yung-Son,Lee, Chia-Fu
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p. 6181 - 6188
(2007/10/03)
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- Acetonyltriphenylphosphonium bromide in organic synthesis: An extremely efficient catalyst for the protection and deprotection of alcohols as alkyl vinyl ethers
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Acetonyltriphenylphosphonium bromide (ATPB) was an extremely effective catalyst in the preparation of THP, THF, and EE ethers as well as cleavage of THP, THF, and EE ethers to the corresponding alcohols. It could be applied to 1°, 2°and 3°alcohols and phenol.
- Hon, Yung-Son,Lee, Chia-Fu
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p. 2389 - 2392
(2007/10/03)
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- Use of Carboxylic Acid-Triphenylprop-2-ynylphosphonium Bromide Adducts for Acylation of Oxygen and Nitrogen Nucleophiles
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Unstable carboxylic acid-triphenylprop-2-ynylphosphonium bromide adducts, i.e. activated vinyl esters (4), prepared in situ under mild conditions, have been used to acylate the oxygen and nitrogen nucleophiles to give the acylated products (5) together with acetonyltriphenylphosphonium bromide (6, X = Br).Acetylmethylenetriphenylphosphorane (7) is conveniently prepared from 6 by treatment with aq.NaOH at 0 deg C.
- Khandker, M. N. I.,Ahmad, A.,Hossain, M. G.
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p. 773 - 775
(2007/10/02)
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