Lithium Hydroxide → HCID 9802192, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of LiOH (90.4 g, 3.76 mol) in 1.3 L water and 1.3 L MeOH, was added a solution of the ester prepared in Example 11 (325 g, 0.75 mol) in 3.9 L THF at rt. The solution turned cloudy. This mixture was heated at 60° C. (pot temperature) for 4 hours, and TLC (50% EtOAc/hexane) analysis showed ca. 50% conversion. A solution of LiOH (30.1 g, 1.25 mol) in water (200 mL) was added to the reaction mixture. After 2 hours, TLC analysis showed ca. 85% reaction. Again, a solution of LiOH (30.1 g, 1.25 mol) in water (200 mL) was added to the reaction mixture. After 2 hours, TLC analysis showed very little starting ester left. After the reaction mixture was cooled to rt, THF and MeOH were removed at a reduced pressure. The residue was diluted with water until the solids dissolved (a total of 60 L of water used). Conc. HCl solution was slowly added to this aqueous solution until pH 2.0–3.0. The solid was collected by filtration, and dried under house vacuum overnight. This solid was stirred with 15 L EtOAc and 2 L of 1N HCl solution for 30 minutes. The EtOAc layer was separated and washed with 1N HCl solution (2×1 L). The organic phase was then washed with water (4×2 L) until pH=5.0–6.0. Under Ar protection, the EtOAc solution was reduced to 2.5 L by normal pressure distillation, then cooled to rt without disturbance. White solid precipitated out. After further cooling in an ice water bath for 2 hours, the solid was filtrated and washed with 500 mL cold EtOAc. After drying under high vacuum at 35° C. to a constant weight, the final product (266 g, 81%, 98% ee,) was collected as a white crystal. 1H NMR (CDCl3) δ 7.82(d, 2H), 7.20(d, 2H), 7.05(d, 1H), 6.75(d, 1H), 6.70(dd, 1H), 4.20(t, 2H), 3.42(q, 1H), 2.95(t, 2H), 2.80(m, 2H), 2.50(m, 1H), 2.35(s, 3H), 2.32(s, 3H), 2.20(m, 1H), 1.90(m, 1H), 1.65(m, 1H), 1.45(m, 1H), 0.90(t, 3H). Chiral purity, 99% ee, [α]D=+16.11(CHCl3), mp 149.5–150.5° C.

Provenance & Evidence