2,2-Dimethoxypropane → 1-((S)-1-(tert-butyldimethylsilyloxy)-3-((R)-2,2-dimethyl-1,3-dioxolan-4-yl)propan-2-yl)-3-(2-chloro-3-fluorobenzyl)-1-methylurea

Participants

Reaction Steps

To a solution of the 1-((2S,4R)-1-(tert-butyldimethylsilyloxy)-4,5-dihydroxypentan-2-yl)-3-(2-chloro-3-fluorobenzyl)-1-methylurea 1 (4.5 g, 10.0 mmol) in DMF (170 mL) were added 2,2-dimethoxypropane (12.45 mL, 100.0 mmol) and PPTS (0.050 g, 0.02 mmol) at 0° C. After 1 h the reaction was warmed up to RT and stirred for an additional 2.5 h. The crude reaction mixture was then added into a saturated aqueous solution of NaHCO3 (350 mL) and extracted with EtOAc (3×300 mL). Combined organic layers were washed with Brine (2×400 mL) and dried over MgSO4. The solution was then concentrated to give 1-((S)-1-(tert-butyldimethylsilyloxy)-3-((R)-2,2-dimethyl-1,3-dioxolan-4-yl)propan-2-yl)-3-(2-chloro-3-fluorobenzyl)-1-methylurea, which was used without further purification. LRMS (M+H+) m/z 490.1.

Provenance & Evidence