One-Pot Etherification of Purine Nucleosides and Pyrimidines
摘要:
A one-pot synthesis of ethers derived from inosine, guanosine, 2'-deoxyguanosine, and pyrimidinones is described Exposure of the heterocycle to 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and Cs2CO3 produces a reactive intermediate, which is converted to the desired ether by subsequent addition of an appropriate alcohol or phenol and Cs2CO3. Although rapid formation of HMPA from BOP can occur in the presence of an alcohol and base, as demonstrated by the reaction with methanol, under appropriate conditions these heteroaryl ethers can be efficiently synthesized
Pd-Catalyzed Debenzylation and Deallylation of Ethers and Esters with Sodium Hydride
作者:Yujian Mao、Ye Liu、Yanwei Hu、Liang Wang、Shilei Zhang、Wei Wang
DOI:10.1021/acscatal.8b00185
日期:2018.4.6
simply that the addition of Pd(OAc)2 as a promotor switches the reactivity of a commonly used base NaH to a nucleophilic reductant. The reactivity is engineered into a palladium-catalyzed reductive debenzylation and deallylation of aryl ethers and esters. This operationally simple, mild protocol displays a broad substrate scope and a broad spectrum of functional group tolerance (>50 examples) and high chemoselectivity
When a mixture of 4-chloroquinazoline (7), an aromatic aldehyde 6, sodium hydride, and a catalytic amount of 1, 3-dimethylbenzimidazolium iodide (1) in tetrahydrofuran (THF) was refluxed with stirring for an appropriate time, the chlorine atom of 7 was replaced with the aroyl group, and the 4-aroylquinazolines 10 were obtained in excellent yields. Similar treatments of 4-chloro-2-methylquinazoline (8) and 4-chloro-2-phenylquinazoline (9) led to the 4-aroyl-2-methylquinazolines 11 and the 4-aroyl-2-phenylquinazolines 12, respectively.Use of N, N-dimethylformamide (DMF) instead of THF as the reaction solvent in the above reaction reduced the reaction time and increased the yields of the ketones 10 and 12 as compared with those in THF.