Reacción #87331

Ecuación de reacción

13

3β-Acetoxy-17-chloro-16-formylandrosta-5,16-diene

6-chloropurine

TBAF

→

21a

3β-Acetoxy-17-(6-Chloro-9H-purin-9-yl)-16-formylandrosta-5,16-diene

Disolventes

THF

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaAfter cooling to room temperature
2. 2
   Concentraciónthe reaction mixture concentrated
3. 3
   workup.ADDITIONpoured onto ice-cold water (250 mL)
4. 4
   Filtraciónthe resulting precipitate was filtered
5. 5
   Lavadowashed with water
6. 6
   Otrodried
7. 7
   Otroto give a crude product
8. 8
   OtroPurification by FCC [DCM/Methanol (9.7:0.3)]
9. 9
   Otrorecrystallized with hot ethanol

Procedimiento

A mixture of 13 (2.43 g, 6.46 mmol), 6-chloropurine (0.5 g, 3.23 mmol) and TBAF (1.69 g, 6.46) in dry THF (40 mL) was stirred at 50° C. under Ar for 48 h. After cooling to room temperature, the reaction mixture concentrated and poured onto ice-cold water (250 mL) and the resulting precipitate was filtered, washed with water and dried to give a crude product. Purification by FCC [DCM/Methanol (9.7:0.3)] and then recrystallized with hot ethanol to give 0.82 g (51.3%) of pure 21a: mp 140-142° C.; IR (Neat) 2943, 2853, 1729, 1672, 1584, 1556, 1435, 1236, 1032, 939, cm-1; 1H NMR (500 MHz, CDCl3) δ 1.07 (s, 3H, 18-CH3), 1.09 (s, 3H, 19-CH3), 2.04 (s, 3H, 3β-OCOCH3), 4.61 (m, 1H, 3α-H), 5.43 (br, 1H, 6-H), 8.20 (s, 1H, 2′-H), 8.79 (s, 1H, aromatic-H), and 9.53 (s, 1H, 16-CHO).

Fuente