Reacción #980153

Ecuación de reacción

sodium borohydride

triethylborane

diethyl methoxyborane

methyl (5S,E)-7-[4,5-bis(4-fluorophenyl)-2-(1-methylethyl)-1H-imidazol-1-yl]-5-hydroxy-3-oxo-6-heptenoate

→

title compound

Rendimiento 48.7%

Methyl (3R,5S,E)-7-[4,5-bis(4-fluorophenyl)-2-(1-methylethyl)-1H-imidazol-1-yl]-3,5-dihydroxy-6-heptenoate

Rendimiento 48.7%

Disolventes

ethyl acetate

methanol

THF

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturathe mixture was cooled to -78°
2. 2
   workup.WAITAfter 4.5 h
3. 3
   Otroquenched with saturated aqueous ammonium chloride solution
4. 4
   OtroThe organic solution was separated
5. 5
   Lavadothe aqueous solution washed with ether (3×)
6. 6
   OtroThe combined organic solutions were dried
7. 7
   Otroevaporated
8. 8
   OtroThe residue was azeotroped with methanol (3×)
9. 9
   Otroto give a brown gum
10. 10
    Lavadoeluting with System A (3:2)

Procedimiento

A mixture of dry THF (4 ml) and dry methanol (1 ml) under nitrogen at room temperature was treated with a solution of triethylborane (1.0M in THF, 0.6 ml). After 1 h, the mixture was cooled to -78°, and a portion of this diethyl methoxyborane solution (1.93 ml) was added to methyl (5S,E)-7-[4,5-bis(4-fluorophenyl)-2-(1-methylethyl)-1H-imidazol-1-yl]-5-hydroxy-3-oxo-6-heptenoate (73.8 mg) under magnetic stirring. The homogeneous solution was stirred for 1 h, then treated with powdered sodium borohydride (98%, 6.4 mg) at -78°. After 4.5 h, the reaction mixture was diluted with ethyl acetate, quenched with saturated aqueous ammonium chloride solution and allowed to warm to room temperature overnight. The organic solution was separated and the aqueous solution washed with ether (3×). The combined organic solutions were dried and evaporated. The residue was azeotroped with methanol (3×) to give a brown gum. This gum was subjected to preparative t.l.c. eluting with System A (3:2), to give the title compound (36.1 mg) as a brown gum, [α]D20 +5.38° (c 1.86, ethyl acetate), δ(CDCl3) 1.40 (d, J 7 Hz, 6H, --CH(CH3)2), 1.4-1.8 (m, 2H, CH(OH)CH2CH(OH)), 2.44 (d, J 5 Hz, 2H, CH2CO2CH3), 3.13 (septet, J 7 Hz, 1H, --CH(CH3)2), 3.73 (s, 3H, OCH3), 3.85 (broad s, 2H, CH(OH)CH2CH(OH)), 4.15 (m, 1H, CH(OH)CH2CO2CH3), 4.42 (m, 1H, =CHCH(OH)CH2), 5.31 (dd, J 15 and 5 Hz, 1H, NCH=CH--), 6.66 (dd, J 15 and 2 Hz, 1H, NCH=CH--), 6.90 (t, J 9 Hz, 2H, C-3 and C-5 protons of 4-(4-fluorophenyl)), 7.09 (t, J 9 Hz, 2H, C-3 and C-5 protons of 5-(4-fluorophenyl)), 7.23 and 7.39 (2 dd, J 9 and 6 Hz, 4H, C-2 and C-6 protons of 4-fluorophenyls).

Fuente