- A New Preparative Route to Substituted Dibenzofurans by Benzannulation Reaction. An Application to the Synthesis of Cannabifuran
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A new regioselective pathway to substituted dibenzofuran derivatives is described here. According to this procedure substituted 1-acetoxy-3- alkoxycarbonyl dibenzofurans are obtained by treatment of 6-(2-methoxyaryl)-3- alkoxycarbonylhex-3-en-5-ynoic acids with acetic anhydride in the presence of sodium acetate. The latter acids are prepared from the easily available substituted o-iodo-anisoles by Sonogashira coupling with propargylic alcohol and Wittig reaction as the key steps. The described benzannulation reaction proceeds in regioselective fashion and a range of substituents are tolerated. Its synthetic utility is demonstrated by a new synthesis of cannabifuran, a naturally occurring dibenzofuran.
- Serra, Stefano,Fuganti, Claudio
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p. 2005 - 2008
(2007/10/03)
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- Palladium- and platinum-catalyzed cyclocarbonylation reactions of substituted allyl acetates
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The scope and limitation of novel palladium-and platinum-catalyzed cyclocarbonylation reactions of 3-arylallyl and 2,4-pentadienyl acetates are described.The detailed mechanism of these reactions is also discussed.
- Ishii, Youichi,Hidai, Masanobu
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p. 279 - 287
(2007/10/02)
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- Palladium-Catalyzed Cyclocarbonylation of 3-(Heteroaryl)allyl Acetates1
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Acetoxybenzofurans, acetoxybenzothiophenes, acetoxyindoles, and acetoxycarbazoles were obtained in high yields by cyclocarbonylation of 3-furyl-, 3-thienyl-, 3-pyrrolyl-, and 3-indolylallyl acetates, respectively, in the presence of Ac2O, NEt3, and a catalytic amount of PdCl2(PPh3)2 at 130 - 170 deg C under 50 - 70 atm of CO. 3-(3-Furyl)allyl and 3-(3-thienyl)allyl acetates cyclized selectively at the 2-position of the heterocyclic nucleus to give 7-acetoxybenzofuran and 7-acetoxybenzothiophene, respectively.The synthetic utility of the reaction was demonstrated by the synthesis of canabifuran from isothymol.
- Iwasaki, Masakazu,Kobayashi, Yoshihiro,Li, Ji-Ping,Matsuzaka, Hiroyuki,Ishii, Youichi,Hidai, Masanobu
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p. 1922 - 1927
(2007/10/02)
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- A BIOGENETIC-TYPE SYNTHESIS OF CANNABIFURAN AND DEHYDROCANNABIFURAN
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The title compounds were synthesized from cannabidiol in yield of 21percent and 29percent respectively.
- Jorapur, Vaman S.,Duffley, Richard P.,Razdan, Raj K.
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p. 203 - 208
(2007/10/02)
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- Synthesis of Cannabis Constituents, Cannabifuran and Dehydrocannabifuran
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Short syntheses of cannabifuran and dehydrocannabifuran, natural dibenzofurans occurring in green Afghan hashish, are described.
- Scannell, Ralph T.,Stevenson, Robert
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p. 321 - 326
(2007/10/02)
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- CANNABIS XXVI. TOTAL SYNTHESIS OF CANNABIFURAN
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The naturally occurring dibenzofuran cannabifuran (10) has been synthesized from 2,3-dimethoxy-p-toluic acid and 2-bromoolivetol dimethyl ether.In the key step, the aryl-aryl bond has been formed via a methoxy displacement in the aryloxazoline (1).The final furan ring closure in (8) to (10) was accomplished by the HI/Ac2O reagent.
- Novak, J.,Salemink, C. A.
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p. 101 - 102
(2007/10/02)
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- Cannabis. Part 28. A New Route to the Synthesis of Cannabifuran
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The total synthesis of the naturally occuring dibenzofuran cannabifuran (9-isopropyl-6-methyl-3-pentyldibenzofuran-1-ol) (25) is presented.In the key step, starting from 2,3-dimethoxy-p-toluic acid and 2-bromo-1,3-dimethoxy-5-pentylbenzene, the aryl-aryl
- Novak, Jiri,Salemink, Cornelis A.
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p. 2873 - 2878
(2007/10/02)
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- Naturally Occurring Dibenzofurans. Part 1. A Synthesis of Cannabifuran
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The synthesis of dibenzofurans from diphenyl ethers by non-phenolic oxidative coupling, u.v. irradiation, and by reaction with palladium(II) acetate has been investigated. 9-Isopropyl-6-methyl-3-pentyldibenzofuran-1-ol (cannabifuran) (35), a minor cannabi
- Sargent, Melvyn V.,Stransky, Peter O.
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p. 1605 - 1610
(2007/10/02)
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