New and efficient RCM in pyridinic series: synthesis of 2H-dihydropyrano- or 2,3H-dihydrooxepino[3,2-b]pyridines

Successive Regioselective Metalations of Fused Heterocycles: Synthesis of Polyfunctionalized Furo[3,2-b]pyridines

“…Purification by centrifugal thin-layer chromatography was performed with cyclohexane/AcOEt: 9/1 to 7/3 as eluent and led to the expected compound 2b (108 mg, 58%) as a brown solid. This derivative is particularly unstable to the light and at room temperature: 1 H NMR and mp are in conformity with literature. 41 2-Chloro-3-tri-n-butylstannylfuro[3,2-b]pyridine 2c.…”

“…Purification by centrifugal thin-layer chromatography was performed with cyclohexane/AcOEt: 10/0 as eluent and led to the expected compound 3a (route A: 63 mg, 40%; route B: 123 mg, 78%) as a white solid: mp 42−44 °C. 1 H NMR δ H (ppm) 0.41 (s, 9H); 0.46 (s, 9H); 7.17 (d, J = 4.7 Hz, 1H); 8.46 (d, J = 4.7 Hz, 1H). 13 C NMR δ C (ppm) −1.4 (3C); −0.6 (3C); 110.9; 123.3; 130.5; 145.0; 149.5; 150.6; 152.4.…”

“…The product 3c was prepared according to the general procedure described herein with chlorotri-n-butyltin (345 mg, 1.06 mmol, 2.0 equiv) as electrophile. Purification by centrifugal thin-layer chromatography was performed with cyclohexane/AcOEt: 10/0 to 98/ 2 as eluent and led to the expected compound 3c (route A: 150 mg, 55%; route B: 237 mg, 87%) as a colorless liquid: 1 2,7-Dichloro-3-trimethylsilylfuro[3,2-b]pyridine 3e. The product 3e was prepared according to the general procedure described in route B with hexachloroethane (251 mg, 1.06 mmol, 2.0 equiv) as electrophile.…”

“…Purification by centrifugal thin-layer chromatography was performed with cyclohexane/AcOEt: 10/0 to 95/5 as eluent and led to the expected compound 3e (127 mg, 92%) as a white solid: mp 48−50 °C. 1 2-Chloro-7-methylthio-3-trimethylsilylfuro[3,2-b]pyridine 3f. The product 3f was prepared according to the general procedure described in route B with dimethyldisulfide (100 mg, 1.06 mmol, 2.0 equiv) as electrophile.…”

One-pot double functionalisation of π-deficient heterocyclic lithium reagents

“…To our knowledge, this reactivity is surprisingly considered as a side reaction. 2 In our continuing efforts aimed at developing simple and efficient synthesis of substituted heterocycles, [3][4][5][6] we describe here an easy procedure leading to bifunctionalised azaheterocycles. Indeed, by using disulfide and amide derivatives as E-Nu trapping reagents (good electrophiles releasing nucleophilic species during the trapping step), the one-pot process combining electrophilic trapping and nucleophilic substitution might be useful to allow the direct preparation of new bifunctional scaffolds (Scheme 1).…”