tert-butyl N-[(2R)-1-hydroxy-4-methylpentan-2-yl]carbamate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Triethylamine (59 ml) and methanesulfonylchloride (25 ml) were added to a THF solution (200 ml) containing (R)-tert-butyl (1-hydroxy-4-methylpentan-2-yl)carbamate (46.2 g) in an ice bath, followed by stirring for 0.5 hours. A saturated sodium hydrogen carbonate aqueous solution was added to the reaction solution, followed by extraction with ethyl acetate. The organic layers were dried over anhydrous sodium sulfate and the solvent was distilled away under reduced pressure. A white solid of (R)-2-((tert-butoxycarbonyl)amino)-4-methylpentyl methanesulfonate (60 g) was thus obtained. followed by extraction with ethyl acetate The organic layers were dried over anhydrous sodium sulfate the solvent was distilled away under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2.1 g of 5-(4-hydroxybenzyl)-3-triphenylmethylthiazolidine-2,4-dione [prepared as described in Preparation 11] were added to a mixture of 2.28 g of 1,1'-azodicarbonyl-dipiperidine, 3.34 ml of tributylphosphine and 100 ml of anhydrous benzene. The resulting mixture was stirred at room temperature for one and a half hours, after which 2 g of 2(R)-t-butoxycarbonylamino-4-methylpentanol [prepared as described in Preparation 15] were added. The mixture was then stirred for a further five hours at the same temperature. At the end of this time, insolubles were filtered off and the filtrate was concentrated. The resulting residue was then purified by column chromatography through silica gel, using a 1:4 by volume mixture of ethyl acetate and hexane as the eluent, to obtain 1.05 g of the title compound, having an Rf=0.54 (thin layer chromatography on silica gel, using a 1:4 by volume mixture of ethyl acetate and hexane as the developing solvent). The mixture was then stirred for a further five hours at the same temperature At the end of this time, insolubles were filtered off the filtrate was concentrated The resulting residue was then purified by column chromatography through silica gel by volume mixture of ethyl acetate and hexane as the eluent