HCID 57099902, compound → HCID 69731064, compound

Participants

Reaction Steps

A mixture of 28.7 g of the compound prepared in Example 13 in 200 ml of tert-butyl methyl ether and 200 ml of 2N NaOH was stirred vigorously at room temperature for 4 hours and then at 50° C. for 20 hours. After cooling, the aqueous phase was extracted twice with 100 ml of tert-butyl methyl ether each time. The organic phases were discarded. The aqueous phase was acidified cautiously with about 70 ml of 6N HCl and extracted once with 200 ml of tert-butyl methyl ether and twice with 100 ml of tert-butyl methyl ether each time. All three organic phases were washed once with 50 ml of 10% sodium chloride solution, combined and dried over sodium sulphate. After removal of the solvent under reduced pressure (40° C./25 mbar) the brown viscous oil was dissolved in 60 ml of isopropyl ether at 60° C. and left to crystallize at -20° C. for 16 hours. The crystals were filtered off, washed with a small amount of isopropyl ether, cooled to -20° C. and dried at 40° C. for hours and 25 mbar, yielding 12.0 g of (3R,4S)-4-hydroxy-azepan-1,3-dicarboxylic acid 1-tert-butyl ester of melting point 98.5-101.5° C.

Provenance & Evidence