Hydrochloric Acid → (2R,3R)-3-((S)-1-(((9H-fluoren-9-yl)methoxy)carbonyl)pyrrolidin-2-yl)-3-methoxy-2-methylpropanoic acid

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Reaction Steps

To a stirring solution of #11 (2.4 g, 8.4 mmol, 1.0 eq.) in 10 mL of dioxane under nitrogen, 4M HCl in dioxane (20 mL, 80 mM, 10 eq.) was added. The reaction was allowed to stir at room temperature for 3 hours before being concentrated in vacuo and placed underneath high vacuum. Crude material was then dissolved with 30 mL of 10% Na2CO3. This solution was then added to a stirring solution of 1-{[(9H-fluoren-9-ylmethoxy)carbonyl]oxy}pyrrolidine-2,5-dione (2.96 g, 8.77 mmol, 1.05 eq.) in 30 mL of DME. Reaction was allowed to stir at room temperature until TLC (20% methanol/40% ethyl acetate/40% heptanes) indicated the consumption of Boc de-protected starting material. The reaction was concentrated in vacuo to a smaller volume, washed twice with ether, acidified to pH 2 using concentrated HCl and then extracted three times with a solution of 90% dichloromethane 10% methanol. The organics where washed with saturated sodium bicarbonate and brine before being dried over sodium sulfate, filtered, and concentrated in vacuo to a brown solid #119 (3.4 g, quant.). LC-MS (Protocol Q): m/z 410.0 [M+H+], retention time=1.81 minutes.

Provenance & Evidence