Tautomerism of quinazolin-4-ones with 2,3-annulated hydrogenated 1,3-diazaheterocycles. Synchronous and asynchronous double proton transfer in cyclic hydrogen-bonded associates
Synthesis of novel 2,3-substituted quinazolin-4-ones by condensation of alkyl or aromatic diamines with 5-(N-arylimino)-4-chloro-5H-1,2,3-dithiazoles
作者:Maria de Fatima Pereira、Valérie Thiéry、Thierry Besson
DOI:10.1016/j.tet.2006.11.028
日期:2007.1
N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-anthranilates to afford quinazolines, which are very interesting starting materials for the access to novel 2,3-condensed quinazolin-4-ones. On the other side, aromatic amines allow the synthesis of polycyclic molecules, which are structurally close to the model natural products (e.g., rutaecarpine, luotonine, tryptanthrine and vasicinone).
本文描述的工作是Appel盐在新型杂环概念中的效用的另一个示例。我们证实,伯烷基二胺可能容易与N-(4-氯-5 H -1,2,3-二噻唑-5-亚甲基)-邻氨基苯甲酸甲酯反应生成喹唑啉,这是获得新颖化合物的非常有趣的起始原料2,3-缩合的喹唑啉-4-酮。另一方面,芳族胺允许合成多环分子,该多环分子在结构上接近模型天然产物(例如,芸香芸香碱,色氨酸,色氨酸和血管紧张素)。
Radical Synthesis of Guanidines from<i>N</i>-Acyl Cyanamides
Center stage: Additions of nitrogen‐centered radicals to cyanamide compounds provided the first radicalsynthesis of aromatic polycyclic guanidine derivatives (see scheme). Modular assembly of the substrates allows for a rapid increase of the molecular complexity of scaffolds, which have potential applications for medicinal chemistry.
Tautomerism of quinazolin-4-ones with 2,3-annulated hydrogenated 1,3-diazaheterocycles. Synchronous and asynchronous double proton transfer in cyclic hydrogen-bonded associates
作者:A. S. Morkovnik、L. N. Divaeva
DOI:10.1007/s11172-009-0111-6
日期:2009.5
It was shown by quantum chemical methods and 1H NMR spectroscopy that in the series of prototropic tautomeric quinazolin-4-ones with hydrogenated 1,3-diazaheterocycles annulated at positions 2 and 3, namely, imidazole, pyrimidine, or [1,3]diazepine (compounds 1–3, respectively), the 1H-tautomeric form strongly predominates in the gas phase and in solutions regardless of the nature of these cycles. Tautomerization of tricycles 1–3 occurs via the intermolecular mechanism to form as intermediates hydrogen-bonded cyclodimers of these compounds or their cyclosolvates with proton-donor solvents. The key step of the reaction is the intraassociated concerted double proton transfer, which can proceed in nearly synchronous and asynchronous modes. In particular, double proton transfer in cyclodimers of quinazolinones 1–3 is asynchronous and proceeds with the formation of solvate-stabilized polar transition states, which are similar in structure to ionic intermediates of the nonconcerted double proton transfer.