2-Bromo-5,5-dimethyl-5H-thieno<3,2-b>pyran | 150194-35-7

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 噻吩并吡喃类
• 英文名称: 2-Bromo-5,5-dimethyl-5H-thieno<3,2-b>pyran
• 英文别名: 2-Bromo-5,5-dimethylthieno[3,2-b]pyran
• CAS: 150194-35-7
• 化学式: C₉H₉BrOS
• 分子量: 245.14
• InChiKey: YHBMJQJNWCVVNA-UHFFFAOYSA-N

物化性质

• 沸点：
  286.6±40.0 °C(predicted)
• 密度：
  1.488±0.06 g/cm3(Temp: 20 °C; Press: 760 Torr)(predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  3.6
• 重原子数：
  12
• 可旋转键数：
  0
• 环数：
  2.0
• sp3杂化的碳原子比例：
  0.33
• 拓扑面积：
  37.5
• 氢给体数：
  0
• 氢受体数：
  2

反应信息

• 作为反应物：
  描述：

  2-Bromo-5,5-dimethyl-5H-thieno<3,2-b>pyran 以 氯仿 为溶剂， 以68%的产率得到(E)-5-Bromo-2-(3-methyl-2-butenylidene)-3-oxo-2H-thiophene
  参考文献：
  名称：

  Thiophene systems. 16. Interesting contrasts in electrocyclic reactions for thieno[3,2-b]- and -[2,3-b]pyrans with chromenes

  摘要：

  Thienopyrans 3, 4, and 5 were synthesized and found to have remarkable differences in stability. Systems 3 and 5 undergo electrocyclic ring-opening to 8 and 18, respectively. In acid milieu at room temperature, system 5 exists in an equilibrium with ring-opened thienopyranone 18. Ground state and activation parameters for the open and closed forms of thienopyrans 3 and 5 as well as the isosteric chromene 2 were calculated using the AM1 Hamiltonian. The Gibbs' free energy differences between the open and closed isomers in each system were found to be predictive of the observed equilibria. The mechanism for ring-opening in both thienopyran systems is proposed to be acid-catalyzed based on the calculated temperatures required for ring-opening as well as experimentally determined results.

  DOI：

  10.1021/jo00069a026
• 作为产物：
  描述：

  5-Bromo-3-methoxy-2-(3-methyl-1-oxo-2-buten-1-yl)thiophene 在 sodium tetrahydroborate 、 三氯化硼 、 对甲苯磺酸 作用下， 以 二氯甲烷 、 甲苯 为溶剂， 反应 21.0h， 生成 2-Bromo-5,5-dimethyl-5H-thieno<3,2-b>pyran
  参考文献：
  名称：

  Thiophene systems. 16. Interesting contrasts in electrocyclic reactions for thieno[3,2-b]- and -[2,3-b]pyrans with chromenes

  摘要：

  Thienopyrans 3, 4, and 5 were synthesized and found to have remarkable differences in stability. Systems 3 and 5 undergo electrocyclic ring-opening to 8 and 18, respectively. In acid milieu at room temperature, system 5 exists in an equilibrium with ring-opened thienopyranone 18. Ground state and activation parameters for the open and closed forms of thienopyrans 3 and 5 as well as the isosteric chromene 2 were calculated using the AM1 Hamiltonian. The Gibbs' free energy differences between the open and closed isomers in each system were found to be predictive of the observed equilibria. The mechanism for ring-opening in both thienopyran systems is proposed to be acid-catalyzed based on the calculated temperatures required for ring-opening as well as experimentally determined results.

  DOI：

  10.1021/jo00069a026