反应详情

Pyridinium bromide perbromide (11.51 g, 36 mmoles) in tetrahydrofuran (25 ml) was added dropwise at 0°-5° C. to a vigorously stirred suspension of the sodium salt of 1-[2-(4,6-dioxo-2,2-dimethyl-1,3-dioxan-5-yl)ethyl]-2-benzoylpyrrole (VI, prepared as described above, 13.5 g, 37.2 mole). The mixture was stirred for 1 hour at 0°-5° C. The mixture was then poured into water (600 ml) and extracted three times with diethyl ether (100 ml, then 2×50 ml). The organic phase was separated and washed with two 200 ml portions of water, dried over magnesium sulfate and evaporated to afford crystalline 1-[2-(5-bromo-4,6-dioxo-2,2-dimethyl-1,3-dioxan-5-yl)ethyl]-2-(benzoyl)pyrrole (VIIa). The product could be recrystallized from ethyl acetate/hexane to give material with the following properties: m.p. 89°-91° C. 1H NMR (CDCl3): delta 1.81 (s, 3H); 2.00 (s, 3H); 3.19 (t, 2H); 4.58 (t, 2H); 6.19 (dd, 1H); 6.71 (dd, 1H); 6.89 (dd, 1H); 7.4-7.55 (m, 3H); 7.78 (dd, 2H). 13C NMR (CDCl3): delta 26.8, 28.9, 39.7, 43.5, 45.8, 107.3, 123.5, 127.9, 129.2, 130.3, 131.4, 139.1, 163.0, 186.9.

1. extractionextracted three times with diethyl ether (100 ml
2. customThe organic phase was separated
3. washwashed with two 200 ml portions of water
4. dry with materialdried over magnesium sulfate
5. customevaporated