Abstract: Piperidine is the most frequently encountered aliphatic heterocycle in medicinal chemistry. Despite its prevalence, there is a constant demand for improvement of ADME (absorption, distribution, metabolism, excretion) properties of piperidine-containing drugs and drug candidates. 2-azabicyclo[2.2.0]hexanes present an exciting class of more rigid and structurally programmable piperidine isosteres. EVA (exit vector analysis) of the most frequently employed piperidine isosteres and 2-azabicyclo[2.2.0]hexanes is presented, and a side-by-side comparison is made. This dissertation describes our endeavors towards the expansion of accessible 2-azabicyclo[2.2.0]hex-5-ene chemical space, our exploration of 2-azabicyclo[2.2.0]hex-5-ene scaffold reactivity in olefin functionalization reactions and installation of synthetically useful handles. The malleability and practicality of 2-azabicyclo[2.2.0]hexane core is demonstrated by preparation of several isosteres of piperidine-containing drugs and lead compounds. A general blueprint for functionalized 2-azabicyclo[2.2.0]hexanes is devised. Special attention is devoted to “pseudoaxial” C5-substituted-2-azabicyclo[2.2.0]hexanes, which could serve as isosteres of piperidines in their thermodynamically unfavorable axial conformations without the need to introduce additional carbon atoms.
La piperidina è l’eterociclo alifatico più frequente nella chimica farmaceutica (medicinal chemistry). Nonostante la sua prevalenza, c’è una costante domanda for il miglioramento delle proprietà ADME (assorbimento, distribuzione, metabolismo, escrezione) di farmaci e candidati farmaci contenenti strutture piperidiniche. Gli 2-azabiciclo[2.2.0]esani rappresentano un’interessante classe di isosteri della piperidina più rigidi e programmabili strutturalmente. L’EVA (exit vector analysis, analisi di vettore di uscita) degli isosteri della piperidina più frequentemente utilizzati e di 2-azabiciclo[2.2.0]esani viene mostrata, ed è stata eseguita una comparazione tra loro. Questa tesi descrive i nostri sforzi verso l’espansione di spazio chimico accessibile dei 2-azabiciclo[2.2.0]es-2-eni, la nostra esplorazione della reattività della struttura di tipo 2-azabiciclo[2.2.0]es-2-ene nelle reazioni di funzionalizzazione delle olefine e l’installazione di appigli sinteticamente utili. La malleabilità e praticabilità del nucleo di tipo 2-azabiciclo[2.2.0]es-2-ene è dimostrata dalla preparazione di diversi isosteri di farmaci e composti guida, contenenti strutture piperidiniche. Un progetto generale per la funzionalizzazione di 2-azabiciclo[2.2.0]es-2-eni è stato elaborato. Un’attenzione particolare è stata riservata ai 2-azabiciclo[2.2.0]es-2-eni con sostituenti sul C5 “psuedoassiali”, che possono servire come isosteri di piperidine nella loro conformazione assiale termodinamicamente sfavorevole, senza la necessità di introdurre atomi di carbonio addizionali.
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With Pd(2+)*2C5F9O2(1-); trifluoroacetic acid; 6-methyl-2,2'-bipyridine; In tetrahydrofuran; water; at 130℃; for 1h;Microwave irradiation;
General procedure: A 2 mL microwave vialwas charged with 6-methyl-2,2'-bipyridine (16.3 mg, 0.096 mmol), Pd(O2CCF3)2(26.6 mg, 0.08 mmol) and 500 muL THF. After stirring at room temperature for 5minutes, <strong>[123843-65-2]2,6-difluoro-4-methoxybenzoic acid</strong> (188.1 mg, 1 mmol), nitrile (5mmol), water (50 muL) and TFA (77 muL, 1 mmol) were added and the mixture heated inthe microwave for 1 hour at 130 C. Themixture was diluted with DCM (15 mL) and 0.1 M NaOH (15 mL), the phases wereseparated and extracted with DCM (2 ×15 mL), dried with Na2SO4, filtered and concentratedunder reduced pressure. Purification by flash chromatography afforded ketones 3p,3x or 3ac in the yields statedin Table 3.
2-(pyridin-3-yl)pyrido[3,4-d]pyrimidin-4(3H)-one dihydrochloride[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
57 mg
A mixture of 3-aminopyridine-4-carboxylic acid (137 mg, 1.0 mmol), nicotinonitrile (125 mg, 1.2 mmol), sodium methoxide (54 mg, 0.25 mmol) in methanol (6 mL) was heated at reflux for 3 days. The mixture was concentrated and dissolved into dimethylformamide and purified by reverse phase-HPLC to give the desired product that was converted to an HCl salt (57 mg) using 4N HCl in dioxane. LC/MS: RT = 1.86 minutes, purity > 95percent, (M+l)+ = 224.98.
Chemistry
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