Triethylamine → (1S,2S,4R)-2-{[(triisopropylsilyl)oxy]methyl}-4-(tritylamino)cyclopentanol

Participants

Reaction Conditions

Reaction Steps

A reactor was charged with the mixture of (1S,2S,4R)-2-(hydroxymethyl)-4-(tritylamino)cyclopentanol and (1S,3S)-1-(hydroxymethyl)-3-(tritylamino)cyclopentanol (1.87 kg total, ˜280 g of (1S,2S,4R)-2-(hydroxymethyl)-4-(tritylamino)cyclopentanol, 0.75 mol). The reactor was charged with methylene chloride (7.4 L) and the agitation started. While maintaining the temperature less than 25° C., triethylamine (210 mL, 1.5 mol) was added. While maintaining the temperature less than 25° C., triisopropylsilyl chloride (402 mL, 1.9 mol) was slowly added. The reaction mixture was allowed to stir at 20° C. to 22° C., for ˜48 hours. The reaction mixture was analyzed by TLC (50% ethyl acetate/heptane, UV visualization), which indicated the formation of the product (Rf 0.70) and the presence of unreacted (1S,3S)-1-(hydroxymethyl)-3-(tritylamino)cyclopentanol (Rf 0.15). The clear pale yellow solution was cooled to 5 to 10° C., slowly quenched with DI water (7.5 L), and the resulting layers separated. The aqueous phase was extracted with methylene chloride (3 L) and the combined organic phases were dried over anhydrous magnesium sulfate, filtered through a pad of diatomaceous earth and concentrated under reduced pressure to give a brown oil (4.06 kg), which was purified by silica gel chromatography using multiple columns. Each column was performed as follows. A 20 cm diameter glass column was loaded with a slurry of silica gel (4.5 kg) in 10% ethyl acetate/heptane. The oil (˜1.2 kg) was loaded on the column. Combined purified material from all columns afforded the title compound (2.94 kg) as a clear oil which was used without further purification. 1H NMR (300 MHz, CDCl3, δ): 7.56-7.54 (m, 5H), 7.34-7.13 (m, 10H), 4.26 (bs, 1H), 3.86-3.81 (dd, J=10.0, 4.5 Hz, 1H), 3.65-3.60 (dd, J=10.1, 7.2 Hz, 1H), 3.41-3.37 (m, 1H), 3.07 (bs, 1H), 2.16-2.07 (m, 1H), 1.69-1.63 (m, 3H), 1.47-1.20 (m, 4H) and 1.08-1.03 (2 s, 18H).

Provenance & Evidence