- A Continuous Flow Strategy for the Facile Synthesis and Elaboration of Semi-Saturated Heterobicyclic Fragments
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An efficient hydrogenation protocol under continuous flow conditions was developed for the synthesis of underrepresented semi-saturated bicyclic fragments containing highly sp3-rich skeletons for fragment-based drug discovery (FBDD) programs. Excellent yields were generally achieved by using Pd/C (10 % w/w) and RaNi at 25–150 °C under 4–100 bar of hydrogen pressure. The generated fragments, with appropriate physicochemical properties, present diverse hydrogen-bonding pharmacophores and useful vectors for their synthetic elaboration in the optimization stage. Successive, simple functionalizations in continuous flow were accomplished to demonstrate the opportunity to develop multi-step continuous flow synthesis of valuable starting points for FBDD campaigns. A conclusive quality control (QC) was essential to discard those structures which do not fit the typical fragment library parameters.
- Luise, Nicola,Wyatt, Eleanor W.,Tarver, Gary J.,Wyatt, Paul G.
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p. 1341 - 1349
(2019/01/14)
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- An annulative transfer hydrogenation strategy enables straightforward access to tetrahydro fused-pyrazine derivatives
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A ruthenium-catalysed annulative transfer hydrogenation strategy, enabling straightforward access to tetrahydro fused-pyrazine derivatives from N-heteroaryl diamines and vicinal diols, has been demonstrated for the first time. Such a synthesis proceeds with unprecedented synthetic effectiveness including high step- and atom efficiency, generation of water as the sole by-product, short reaction time and no need for external high pressure H2 gas, offering an important basis for the transformation of vicinal diols, a class of bio-mass derived resources, into functionalized products.
- Xiong, Biao,Zhang, Shu-Di,Chen, Lu,Li, Bin,Jiang, Huan-Feng,Zhang, Min
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supporting information
p. 10636 - 10639
(2016/09/02)
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- 3,4-diaminopyridine derivatives
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3,4-Diaminopyridine derivatives corresponding to a specified formula are produced by (a) reacting 3,4-diaminopyridine with a 1,2-dicarbonyl compound to form a diimine; (b) reducing the diimine to a diamine; and (c) replacing at least a hydrogen atom on nitrogen at position 4 of the pyridine ring. These compounds are useful as catalysts.
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Page/Page column 4-5; 9
(2008/12/07)
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- Development of more potent 4-dimethylaminopyridine analogues
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The syntheses of bicyclic diaminopyridines 3 and 4 and tricyclic triaminopyridines 5 and 6, two novel series of nucleophilic catalysts, are described. Arguments are made for predicting the superiority of these catalysts over DMAP and even 2, the best esterification catalyst reported to date. The efficiencies of DMAP, PPY, and 2-6 in catalyzing the esterification of tertiary alcohols were compared. As predicted, 5 and 6 were about 6-fold more effective than DMAP and slightly better than 2.
- Singh, Satwinder,Das, Goutam,Singh, Om V.,Han, Hyunsoo
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p. 401 - 404
(2008/02/12)
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- Modular design of pyridine-based acyl-transfer catalysts
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Derivatives of 3,4-diaminopyridine have been synthesized and studied as catalysts for acyl-transfer reactions. The design of these catalysts is guided by the stability of their acetyl intermediates as determined through theoretical calculations at the B3LYP/6-311 + G(d,p)//B3LYP/6-31G(d) level of theory. The most promising catalysts have been synthesized through a three- to five-step synthesis starting from 3,4-diaminopyridine. The catalytic activity has been determined for the acylation of 1-ethynylcyclohexanol with acetic anhydride at 23°C and with isobutyric anhydride at 40°C. For both reactions, the catalytic activity depends dramatically on the substitution pattern of the diaminopyridines. Best results are obtained with catalysts containing alkyl substituents at both amine nitrogens. Georg Thieme Verlag Stuttgart.
- Held, Ingmar,Xu, Shangjie,Zipse, Hendrik
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p. 1185 - 1196
(2008/02/02)
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