Imidazole → 2-bromo-(R)-1-tert-butyldimethylsiloxy-1-(3-formamido-4-benzyloxyphenyl)ethane

Participants

Reaction Conditions

Reaction Steps

A solution of TBDMS-Cl (40.1 g, 0.26 mol) in DCM (37.5 mL) was added to a slurry of imidazole (21.86 g, 0.32 mol) and (R)-2-bromo-1-(3-formamido-4-benzyloxyphenyl)ethanol (74.54 g, 0.21 mol) in DCM (260 mL) over 8 minutes. The mixture was stirred for 22 hours. The reaction was quenched with water (190 mL) and the aqueous layer was extracted with DCM (37.5 mL). The combined DCM layers were distilled at atmospheric pressure to a volume of ca. 110 mL. On cooling, spontaneous crystallisation occurred. Isooctane (750 mL) was added dropwise over 20 minutes. The slurry was cooled to 0° C. and the solids were collected by filtration then washed with 9:1 v/v isooctane:DCM (3×75 mL) and dried in vacuo to give the title compound as a colourless solid (89.65 g, 90% th). 1H NMR in accord with structure (400 MHz, CDCl3) δ(ppm): −0.06 (3H) s; 0.11 (3H) s; *0.12 (3H) s; *0.89 (9H) s; 0.90 (9H) s; *3.38-3.49 (2H) m; 4.78-4.87 (1H) m; *5.09 (2H) s; 5.10 (2H) s; 6.96 (1H) d, J=8.6 Hz; *7.06 (1H) d of d, J=8.3, 2.0 Hz; 7.11 (1H) d of d, J=8.3 Hz, 2.0 Hz; 7.25-7.27 (1H) m; 7.36-7.45 (5H) m; *7.70 (1H) d, J=11.0 Hz; 7.79 (1H) s; 8.38 (1H) d, J=2.0 Hz; 8.42 (1H) d, J=1.5 Hz; *8.76 (1H) d, J=11.8 Hz. *Peaks are due to ca 25M % of the minor rotamer.

Provenance & Evidence