Synthesis of polyfunctionalized furans from 3-acetyl-1-aryl-2-pentene-1,4-diones
摘要:
The BF3-catalyzed cyclization of 3-acetyl-1-aryl-2-pentene-1,4-diones 1a-e in the presence of water in boiling tetrahydrofuran gave bis(3-acetyl-5-aryl-2-furyl)methanes 2a-e in 26-79% yields along with a small amount of 3-acetyl-5-aryl-2-methylfurans 3a-e. The exact structure of 2a was determined by X-ray crystallography. The use of a half volume of the solvent for the reaction of la resulted in the formation of 2,4-bis(3-acetyl-5-phenyl-2-furfuryl)-3-acetyl-5-phenylfuran (4) together with 2a and 3a. A similar reaction of la was carried out in the presence of 3-acetyl-5-(4-methylphenyl)-2-methylfuran (3d) to afford 4-(3-acetyl-5-phenyl-2-furfuryl)-3-acetyl-5-(4methylphenyl)-2-methylfuran (5) in 49% yield. The BF3-catalyzed reaction of la with 2,4-pentanedione in dry tetrahydrofuran at 23degreesC gave 3-(3-acetyl-5-phenyl-2-furfuryl)-4-hydroxy-3-penten-2-one (6a) and 3-(3-acetyl-2-methyl-4-phenyl-5-furyl)-4-hydroxy-3-penten-2one (7a) in 66 and 24% yields, respectively. The product distribution depended on the reaction temperature. A similar reaction of 1b-e also yielded the corresponding trisubstituted furans 6b-e and tetrasubstituted furans 7b-e in good yields. These results suggested the presence of the furfuryl carbocation intermediate A during the reaction. The one-pot synthesis of 6a and 7a was also achieved by a similar reaction using phenylglyoxal. The deoxygenation of la with triphenylphosphine gave 3a in 88% yield, while la was treated with concentrated hydrochloric acid to yield 3-acetyl-2-chloromethyl-5-phenylfuran (8) which was quantitatively transformed in ethanol into 3-acetyl-2-ethoxymethyl-5phenylfuran (9) and in water into 3-acetyl-5-phenylfurfuryl alcohol (10), respectively. In addition, the Diels-Alder reaction of cyclopantadiene with 1a gave the corresponding [4+2] cycloaddition products 11 and 12. (C) 2003 Elsevier Science Ltd. All rights reserved.
Reaction of Electron-Deficient 3-Acetyl-1-arylpent-2-ene-1,4-diones as a Building Block of Heterocycles
作者:Hiroshi Nishino、Shun Kawabata、Akihiro Oishi
DOI:10.3987/com-17-13736
日期:——
gave unique 3a,6a-dihydrospirofuro[2,3-d][1,3]dioxoles 3 in good to high yields. A similar reaction with the 2,3-dihydroquinolin-4(1H)-ones did not occur, but the reaction with 4-hydroxychromenone 5 mainly produced 3-furfuryl-4-hydroxychromenone 6 along with furochromenone 7. The reaction of the electron-deficient pentenedione 1a as a Michael acceptor with indole, pyrrole, furan, and N-methylaniline produced
2-Indolymethanols as 4-atom-synthons in oxa-Michael reaction cascade: access to tetracyclic indoles
作者:Tian-Jiao Han、Min-Can Wang、Guang-Jian Mei
DOI:10.1039/d1cc03653j
日期:——
The first Brønstedacid-catalyzed oxa-Michael reactioncascade of 2-indolylmethanols with trione alkenes was accomplished. By using this practical approach, a variety of tetracyclic indoles were readily created in an ordered sequence with excellent regio- and diastereoselectivity. 2-Indolylmethanols commendably served as four-atom synthons, as opposed to the common three-atom synthons in the previous
Phosphine-catalyzed divergent domino processes between γ-substituted allenoates and carbonyl-activated alkenes
作者:Mingyue Wu、Zhaobin Han、Huanzhen Ni、Nengzhong Wang、Kuiling Ding、Yixin Lu
DOI:10.1039/d1sc06364b
日期:——
Highly enantioselective and chemodivergent domino reactions between γ-substituted allenoates and activated alkenes have been developed.
已经开发出高度对映选择性和化学多样性的多米诺反应,该反应涉及γ取代的烯酸酯和活性烯烃之间的反应。
Acid-catalyzed convenient transformation of 1-aryl-2-pentene-1,4-diones into polyfunctionalized furans
作者:Satoaki Onitsuka、Hiroshi Nishino、Kazu Kurosawa
DOI:10.1016/s0040-4039(00)00373-7
日期:2000.4
of boron trifluoride gave the unstable 3-acetyl-1-phenyl-2-pentene-1,4-dione intermediate which was converted in situ by the reaction with an excess amount of 2,4-pentanedione into new crystalline tri- and tetra-substituted furans. Other unstable 1-aryl-2-pentene-1,4-diones, which were obtained by the photooxygenation of 3-acetyl-5-aryl-2-methylfurans, were trapped by the acid-catalyzed reaction, giving
Catalyst-free racemic and H<sub>2</sub>O/CPA-catalyzed asymmetric regio-reversed domino processes of triketone enones with azlactones
作者:Yun-Dong Fu、Xiang Gao、Shi-Kun Jia、Xiao Xiao、Min-Can Wang、Lihua Huang、Guang-Jian Mei
DOI:10.1039/d3gc01445b
日期:——
Regio-reversed domino processes of triketone enones with azlactones have been established. Opposite to the previous β-addition-triggered domino processes, this protocol is initiated by a regio-reversed α-addition. Under catalyst-free conditions, the dominoreaction readily occurred, leading to the formation of a variety of bicyclic furofurans bearing vicinal quaternary carbons in good to excellent