Pelletier Jeffrey C, Velvadapu Venkata, McDonnell Mark E, Wrobel Jay E, Reitz Allen B
Fox Chase Chemical Diversity Center, Inc., 3805 Old Easton Rd., Doylestown, PA 18902.
Tetrahedron Lett. 2014 Jul 23;55(30):4193-4195. doi: 10.1016/j.tetlet.2014.05.046.
We have found that α-amino acid amide derivatives of 2-aminobenzothiazoles undergo a time-dependent, thermal rearrangement in which the amine group attacks the 2-position carbon of the thiazole ring to form a 5,5-spiro ring system. This is followed by sulfur leaving and air oxidation to the corresponding symmetrical disulfide. The isolated yields of such products are quite high (>70%) if there is conformational bias to further promote the intramolecular reaction such as for the 2-aminobenzothiazole amides derived from proline or 4-aminopiperidine-4-carboxylic acid. This rearrangement has not been described previously for α-amino acid amide derivatives of 2-aminobenzothiazoles. However, a related reaction involving 2-semicarbazido benzothiazoles has been recently reported.
我们发现，2-氨基苯并噻唑的α-氨基酸酰胺衍生物会发生时间依赖性的热重排反应，其中胺基会进攻噻唑环的2-位碳原子，形成一个5,5-螺环体系。接着硫离去并被空气氧化为相应的对称二硫化物。如果存在构象偏向以进一步促进分子内反应，例如由脯氨酸或4-氨基哌啶-4-羧酸衍生的2-氨基苯并噻唑酰胺，此类产物的分离产率相当高（>70%）。此前尚未有关于2-氨基苯并噻唑的α-氨基酸酰胺衍生物这种重排反应的描述。然而，最近报道了一个涉及2-氨基脲基苯并噻唑的相关反应。
