反应详情

To a cold (˜0° C., ice/water bath) mixture of 2-amino-6-chloropurine (2.2 g. 13.2 mmol), 4 (3.9 g, 12 mmol), triphenylphosphine (3.52 g, 13.4 mmol) in 50 ml of anhydrous THF was added with stirring 2.75 ml (13.9 mmol) of diisopropylazodicarboxylate. The reaction was stirred at room temperature for 5 hrs. The solvent was removed in vacuo and the residue chromatographed on silica eluting with a gradient of ethyl acetate (20-66%) in hexane. The product-containing fractions were pooled and concentrated to afford a semi-crystalline material, which was re-suspended in 20% ethyl acetate/hexane and filtered to remove insoluble hydrazine bis(isopropyl)carbamate. Concentration of the filtrate and drying in vacuo afforded 4.3 g (75%) of 24 as a white solid. 1H NMR, (DMSO-d6): δ 8.09 (s, 1H), 7.4-7.2 (m, 5H), 6.85 (s, 2H), 4.36 (s, 2H), 4.19 (m, 1H), 4.06 (m, 1H), 3.96 (m, 1H), 3.38 (m, 2H), 2.33 (m, 1H), 1.16 (d, J=6 Hz, 3H), 0.85 (s, 9H), 0.17 (s, 3H), 0.00 (s, 3H).

1. additionwas added
2. customThe solvent was removed in vacuo
3. customthe residue chromatographed on silica eluting with a gradient of ethyl acetate (20-66%) in hexane
4. concentrationconcentrated
5. customto afford a semi-crystalline material, which
6. filtrationfiltered
7. customto remove insoluble hydrazine bis(isopropyl)carbamate
8. customConcentration of the filtrate and drying in vacuo