(1R,6S,7R,8R)-7-(3,4-dimethoxyphenyl)-4-methoxy-1,8-dimethylbicyclo[4.2.0]oct-3-ene-2,5-dione

• 分子结构分类: 有机化合物 - 苯类化合物 - 苯和取代衍生物
• 英文名称: (1R,6S,7R,8R)-7-(3,4-dimethoxyphenyl)-4-methoxy-1,8-dimethylbicyclo[4.2.0]oct-3-ene-2,5-dione
• 化学式: C₁₉H₂₂O₅
• 分子量: 330.381
• InChiKey: UBKQQQIVNQMZJZ-OVMPGVDVSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  2.6
• 重原子数：
  24
• 可旋转键数：
  4
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.47
• 拓扑面积：
  61.8
• 氢给体数：
  0
• 氢受体数：
  5

反应信息

• 作为反应物：
  描述：

  (1R,6S,7R,8R)-7-(3,4-dimethoxyphenyl)-4-methoxy-1,8-dimethylbicyclo[4.2.0]oct-3-ene-2,5-dione 在 三氟乙酸 作用下， 以 四氢呋喃 为溶剂， 反应 14.0h， 以26%的产率得到2-甲氧基-5-甲基-1,4-苯醌
  参考文献：
  名称：

  Regioselective Lewis Acid-Directed Reactions of 2-Alkoxy-5-alkyl-1,4-benzoquinones with Styrenes: Synthesis of Burchellin and Guianin Neolignans

  摘要：

  Reactions of 2-carbomethoxy-5-methoxy-1,4-benzoquinone with (E)-propenylbenzenes promoted by Ti(IV) regio- and stereoselectively yield trans 2-aryl-4-carbomethoxy-7-methoxy-3-methyl-2,3-dihydro-5-benzofuranols. However, the products found in Lewis acid-promoted reactions of 2-alkoxy-5-alkyl-1,4-benzoquinones with (E)-propenylbenzenes depend on the nature of the Lewis acid. Low-temperature reactions with SnCl4 produce rel-(1R,6S,7S,8R)-4-alkoxy-1-alkyl-7-aryl-8-methylbicyclo[4.2.0]oct-5-ene-2,5-diones 21-23 and products derived from them. Allowing the reactions to warm to room temperature results in rel-(2S,3S,3aR)-3a-alkyl-2-aryl-5-hydroxy-3-methyl-2,3,3a,6-tetrahydro-6-oxobenzofurans as mixtures of keto-enol tautomers 26/27 and 28/ 29. With Ti(IV) as promoter, the reactions can be made to produce either 21-23 or the regioisomeric rel-(1S,6R,7R,8S)-4-alkoxy-1-alkyl-8-aryl-7-methylbicyclo[4.2.0]oct-3-ene-2,5-diones 18-20. The ratio of the two depends upon the makeup of the Ti(IV) promoter and the substituents on the propenylbenzene. A mechanistic rationale is presented involving regioselective coordination of the different Lewis acids to the quinone. Thus, SnCl4 binds to the C-1 carbonyl and C-2 alkoxy oxygens, forming a complex possessing a 2-alkoxy-5-alkyl-4-oxa-2,5-cyclohexadienyl carbocation moiety (e.g. 30) which undergoes a thermally allowed 4 pi + 2 pi (5 + 2) cycloaddition with propenylbenzene to give a bicyclo[3.2.1]octenyl carbocation 31; this cation then rearranges to the observed products. On the other hand, the Ti(IV)-promoted reactions give either bicyclo[3.2.1]octenyl carbocation 31 or 34, depending upon reaction conditions, followed by rearrangement. Cyclobutanes 18-20 undergo protic acid rearrangement to give trans 7-alkoxy-4-alkyl-2-aryl-3-methyl-2,3-dihydro-5-benzofuranols 15-17, whereas cyclobutanes 21-23 yield 5-alkyl-7-aryl-3-hydroxy-6-methylbicyclo[3.2.1]oct-3-ene-2,8-diones 24/25. The reactions provide an efficient and stereoselective route to neolignans of the guianin and burchellin classes.

  DOI：

  10.1021/jo00101a017
• 作为产物：
  描述：

  2-甲氧基-5-甲基苯酚 在 potassium nitrososulfonate 、 四氯化锡 作用下， 以 二氯甲烷 为溶剂， 反应 16.0h， 生成 (1R,6S,7R,8R)-7-(3,4-dimethoxyphenyl)-4-methoxy-1,8-dimethylbicyclo[4.2.0]oct-3-ene-2,5-dione
  参考文献：
  名称：

  Regioselective Lewis Acid-Directed Reactions of 2-Alkoxy-5-alkyl-1,4-benzoquinones with Styrenes: Synthesis of Burchellin and Guianin Neolignans

  摘要：

  Reactions of 2-carbomethoxy-5-methoxy-1,4-benzoquinone with (E)-propenylbenzenes promoted by Ti(IV) regio- and stereoselectively yield trans 2-aryl-4-carbomethoxy-7-methoxy-3-methyl-2,3-dihydro-5-benzofuranols. However, the products found in Lewis acid-promoted reactions of 2-alkoxy-5-alkyl-1,4-benzoquinones with (E)-propenylbenzenes depend on the nature of the Lewis acid. Low-temperature reactions with SnCl4 produce rel-(1R,6S,7S,8R)-4-alkoxy-1-alkyl-7-aryl-8-methylbicyclo[4.2.0]oct-5-ene-2,5-diones 21-23 and products derived from them. Allowing the reactions to warm to room temperature results in rel-(2S,3S,3aR)-3a-alkyl-2-aryl-5-hydroxy-3-methyl-2,3,3a,6-tetrahydro-6-oxobenzofurans as mixtures of keto-enol tautomers 26/27 and 28/ 29. With Ti(IV) as promoter, the reactions can be made to produce either 21-23 or the regioisomeric rel-(1S,6R,7R,8S)-4-alkoxy-1-alkyl-8-aryl-7-methylbicyclo[4.2.0]oct-3-ene-2,5-diones 18-20. The ratio of the two depends upon the makeup of the Ti(IV) promoter and the substituents on the propenylbenzene. A mechanistic rationale is presented involving regioselective coordination of the different Lewis acids to the quinone. Thus, SnCl4 binds to the C-1 carbonyl and C-2 alkoxy oxygens, forming a complex possessing a 2-alkoxy-5-alkyl-4-oxa-2,5-cyclohexadienyl carbocation moiety (e.g. 30) which undergoes a thermally allowed 4 pi + 2 pi (5 + 2) cycloaddition with propenylbenzene to give a bicyclo[3.2.1]octenyl carbocation 31; this cation then rearranges to the observed products. On the other hand, the Ti(IV)-promoted reactions give either bicyclo[3.2.1]octenyl carbocation 31 or 34, depending upon reaction conditions, followed by rearrangement. Cyclobutanes 18-20 undergo protic acid rearrangement to give trans 7-alkoxy-4-alkyl-2-aryl-3-methyl-2,3-dihydro-5-benzofuranols 15-17, whereas cyclobutanes 21-23 yield 5-alkyl-7-aryl-3-hydroxy-6-methylbicyclo[3.2.1]oct-3-ene-2,8-diones 24/25. The reactions provide an efficient and stereoselective route to neolignans of the guianin and burchellin classes.

  DOI：

  10.1021/jo00101a017

文献信息

• Lewis Acid-Directed Reactions of Quinones with Styrenyl Systems:  The Case of 2-Methoxy-3-methyl-1,4-benzoquinone
  作者：Thomas A. Engler、Rajesh Iyengar

  DOI：10.1021/jo971937u

  日期：1998.3.1

  Reactions of 2-methoxy-3-methyl-1,4-benzoquinone with various (E)-1-propenylbenzenes promoted by 1 equiv of Ti(IV), as a 1:1 mixture of TiCl4-Ti(O-i-Pr)(4), produce rel-(1S, 6R, 7R, 8R)-8-aryl-4,7-dimethyl-3-methoxybicyclo[4.2.0]oct-3-ene-2,5-diones 3 and trans-2-aryl-3,7-dimethyl-6-methoxy-2,3-dihydro-5-benzofuranols 5 as the major products. Reactions promoted by 2 equiv of Ti(IV) as a 1:1 mixture of TiC1l(4)-Ti(O-i-Pr)(4) or 1 equiv of either TiCl4, SnCl4, or BF3 . OEt2 give regioisomeric rel-(1R, 6S, 7R, 8R)-7-aryl-4,8-dimethyl-3-methoxybicyclo[4.2.0]oct-3-ene-2,5-diones (4) and/or trans-2-aryl-3,6-dimethyl-7-methoxy-2,3-dihydro-5-benzofuranols (6). A mechanism involving regioselective coordination of the various Lewis acids to the quinone is used to explain the formation of the products. These reactions demonstrate the effective regiocontrol exerted over the reactions by the nature of the Lewis acid promoters. Cyclobutanes 3 and 4 cleanly undergo rearrangement to the corresponding benzofuranols 5 and 6 on treatment with protic acid. In contrast, reactions of 2-methoxy-1,4-benzoquinone promoted by either BF3 . OEt2 or Ti(IV), as 1 equiv or excess amounts of TiCl4 or 1:1 TiCl4-Ti(O-i-Pr)(4), all afford the same regioisomeric products, i.e., rel-(1S, 6R, 7R, 8R)-8-aryl-7-methyl-3-methoxybicyclo[4.2.0]oct-3-ene-2,5-dione 25 and/or trans-2-aryl-3-methyl-6-methoxy-2,3-dihydro-5-benzofuranol 27.