Sonogashira Couplings Catalyzed by Fe Nanoparticles Containing ppm Levels of Reusable Pd, under Mild Aqueous Micellar Conditions
作者:Sachin Handa、Bo Jin、Pranjal P. Bora、Ye Wang、Xiaohua Zhang、Fabrice Gallou、John Reilly、Bruce H. Lipshutz
DOI:10.1021/acscatal.9b00007
日期:2019.3.1
Nanoparticles derived from FeCl3 containing the ligand XPhos and only 500 ppm Pd effect Sonogashiracouplings in water between rt and 45 °C. The entire aqueous reaction medium can be easily recycled using an “in-flask” extraction. Several tandem processes in one pot are illustrated, including a sequence involving five steps (10 reactions) in good overall yield.
Macrocyclic 5-bromouracil derivatives: synthesis and transformation of a uracil ring
作者:Anton E. Nikolaev、Vyacheslav E. Semenov、Dilyara R. Sharafutdinova、Yurii Ya. Efremov、Vladimir S. Reznik
DOI:10.1016/j.tetlet.2008.07.164
日期:2008.10
Cyclization of 1,3-bis(ω-bromoalkyl)-5-bromouracil with p-methoxybenzylamine or sodium sulfide led to a series of pyrimidinophanes containing heteroatoms in bridges. An unusual behaviour of the 5-bromouracil ring, namely its contraction into hydantoin units during the cyclization reactions with p-methoxybenzylamine was observed. Sodium sulfide does not affect the 5-bromouracil ring, and no transformation
Mild and Robust Stille Reactions in Water using Parts Per Million Levels of a Triphenylphosphine‐Based Palladacycle
作者:Balaram S. Takale、Ruchita R. Thakore、Gianluca Casotti、Xaiohan Li、Fabrice Gallou、Bruce H. Lipshutz
DOI:10.1002/anie.202014141
日期:2021.2.19
triphenylphosphine‐based palladacycle has been developed as a pre‐catalyst, leading to highly effective Stille cross‐couplingreactions in water undermildreactionconditions. Only 500–1000 ppm of Pd suffices for couplings involving a variety of aryl/heteroaryl halides with aryl/hetaryl stannanes. Several drug intermediates can be prepared using this catalyst in aqueous nanoreactors formed by 2 wt % Brij‐30 in
The evaluation of 5-amino- and 5-hydroxyuracil derivatives as potential quadruplex-forming agents
作者:Gábor Paragi、Zoltán Kupihár、Gábor Endre、Célia Fonseca Guerra、Lajos Kovács
DOI:10.1039/c6ob02574a
日期:——
blocks in quadruplex structures. Our high level Density Functional Theory (DFT) calculations showed that the tetramer formation and stacking energies for 5-substituted uracils are similar to the energies of purine-based xanthine (X) or guanine (G) structures. As tetrads of 5-substituted uracils cover almost exactly the same area as purine tetrads, mixed tetrads or quadruplex structures based on X or G and
Sustainable HandaPhos-<i>ppm</i> Palladium Technology for Copper-Free Sonogashira Couplings in Water under Mild Conditions
作者:Sachin Handa、Justin D. Smith、Yitao Zhang、Balaram S. Takale、Fabrice Gallou、Bruce H. Lipshutz
DOI:10.1021/acs.orglett.7b03621
日期:2018.2.2
Complexation of ca. 1000 ppm Pd(OAc)(2) with the ligand HandaPhos (1-1.5:1) leads to a precatalyst that efficiently mediates Sonogashira couplings in aqueous nano micelles under very mild conditions. Neither copper nor organic solvent is required in the reaction medium, and the product can be isolated directly from the reaction flask, leaving behind a reaction mixture that can be recycled without additional additives.