2,5-dimethyl-3,4-diethylfuran | 91819-68-0

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 杂芳族化合物
• 英文名称: 2,5-dimethyl-3,4-diethylfuran
• 英文别名: 3,4-Diethyl-2,5-dimethylfuran；3,4-diethyl-2,5-dimethyl-furan
• CAS: 91819-68-0
• 化学式: C₁₀H₁₆O
• 分子量: 152.236
• InChiKey: OGZKRWWSHUWTCQ-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  3.4
• 重原子数：
  11
• 可旋转键数：
  2
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.6
• 拓扑面积：
  13.1
• 氢给体数：
  0
• 氢受体数：
  1

反应信息

• 作为产物：
  描述：

  3,4-diethyl-hexane-2,5-dione 在 对甲苯磺酸 作用下， 以 苯 为溶剂， 反应 1.0h， 以70%的产率得到2,5-dimethyl-3,4-diethylfuran
  参考文献：
  名称：

  Intermediates in the Paal-Knorr Synthesis of Furans

  摘要：

  New experimental evidence for the mechanism of the Paal-Knorr reaction involving the acid-catalyzed cyclization of a 1,4-diketone to form a furan is reported. In aqueous or alcoholic solutions containing hydrochloric acid and in chloroform containing boron trifluoride-etherate d,l- and meso-3,4-diethyl-2,5-hexanediones (2r and 2m) cyclize at unequal rates; the stereochemical configuration of the unchanged done is preserved during the reaction. This disagrees with the commonly accepted mechanism involving the ring closure of the rapidly formed monoenol (11b) followed by loss of water. A pathway involving the rapid protonation of one of the carbonyls followed by the electrophilic attack on the protonated carbonyl by the enol being formed at the other carbonyl group (10c) is proposed to account for the difference in reaction rates between the diastereomers of 3,4-disubstituted 2,5-hexanediones (1-3). The following results also seem to support the intermediacy of 10c. The presence of two isopropyl groups in 3,4-diisopropyl-2,5-hexanedione (3) considerably reduces the rate of cyclization, The catalytic constants k(H)(+) for the cyclization of 2r and 2m are larger than the constants for enolization of methyl ketones. The diastereomers of 2,3-dimethyl-and 2,3-diethyl-1,4-diphenyl-1,4-butanediones (4 and 5), which could enolize only toward the center of the molecule, also react at different rates. The d,l and meso dideuterio analogs (d(2)-4r and d(2)-4m) exhibit a primary isotope effect during cyclization. The order of cyclization of 1,4-diphenyl-1,4-butanedione (6) and its analogs (7-9) reveals that the presence of electron-donating groups facilitate the reaction.

  DOI：

  10.1021/jo00107a006

文献信息

• The efficient one-pot synthesis of tetraalkyl substituted furans from symmetrical acetylenes, EtAlCl2, and carboxylic esters catalyzed by Cp2TiCl2
  作者：Mariya G. Shaibakova、Leila O. Khafizova、Nuri M. Chobanov、Rinat R. Gubaidullin、Natal’ya R. Popod’ko、Usein M. Dzhemilev

  DOI：10.1016/j.tetlet.2014.01.015

  日期：2014.2

  A new one-pot method for the synthesis of tetraalkyl substituted furans in 74–80% yields has been implemented via the reaction between symmetrical acetylenes, ethylaluminum dichloride, and carboxylic esters in the presence of metallic Mg as an acceptor of halide ions, catalyzed by bis(cyclopentadienyl)titanium dichloride. A mechanism for the reaction is proposed and discussed.

  在金属镁作为卤离子受主的条件下，通过对称乙炔，二氯化乙基铝和羧酸酯之间的反应，已经实现了一种新的一锅法合成四烷基取代的呋喃，产率为74-80％。双（环戊二烯基）二氯化钛。提出并讨论了反应机理。
• US7582712B1
  申请人：——

  公开号：US7582712B1

  公开（公告）日：2009-09-01
• Intermediates in the Paal-Knorr Synthesis of Furans
  作者：Venkataraman Amarnath、Kalyani Amarnath

  DOI：10.1021/jo00107a006

  日期：1995.1

  New experimental evidence for the mechanism of the Paal-Knorr reaction involving the acid-catalyzed cyclization of a 1,4-diketone to form a furan is reported. In aqueous or alcoholic solutions containing hydrochloric acid and in chloroform containing boron trifluoride-etherate d,l- and meso-3,4-diethyl-2,5-hexanediones (2r and 2m) cyclize at unequal rates; the stereochemical configuration of the unchanged done is preserved during the reaction. This disagrees with the commonly accepted mechanism involving the ring closure of the rapidly formed monoenol (11b) followed by loss of water. A pathway involving the rapid protonation of one of the carbonyls followed by the electrophilic attack on the protonated carbonyl by the enol being formed at the other carbonyl group (10c) is proposed to account for the difference in reaction rates between the diastereomers of 3,4-disubstituted 2,5-hexanediones (1-3). The following results also seem to support the intermediacy of 10c. The presence of two isopropyl groups in 3,4-diisopropyl-2,5-hexanedione (3) considerably reduces the rate of cyclization, The catalytic constants k(H)(+) for the cyclization of 2r and 2m are larger than the constants for enolization of methyl ketones. The diastereomers of 2,3-dimethyl-and 2,3-diethyl-1,4-diphenyl-1,4-butanediones (4 and 5), which could enolize only toward the center of the molecule, also react at different rates. The d,l and meso dideuterio analogs (d(2)-4r and d(2)-4m) exhibit a primary isotope effect during cyclization. The order of cyclization of 1,4-diphenyl-1,4-butanedione (6) and its analogs (7-9) reveals that the presence of electron-donating groups facilitate the reaction.