(-)-(r)-Menthyl chloroformate

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

Procedure: Water (40 mL) was added to a yellow solution of 7-amino-5-(4-methoxy-benzyl)-5H,7H-dibenzo[b,d]azepin-6-one (7.45 g) in THF (40 mL) at room temperature forming a light yellow suspension. To this suspension were added K2CO3 (5.53 g) in one portion and, after 15 minutes of stirring, (−)-(1R)-menthyl chloroformate (4.96 g) was added within 30 minutes. The dropping funnel was washed with THF. The emulsion was stirred for 105 minutes at room temperature. Heptane (486 mL) was added within 40 minutes and, after 60 more minutes of stirring, the precipitate was filtered off, washed with heptane, water, and then heptane in that order and dried under vacuum at 55° C. to afford [(S)-5-(4-methoxy-benzyl)-6-oxo-6,7-dihydro-5H-dibenzo[b,d]azepin-7-yl]-carbamic acid (1R,2S,5R)-2-isopropyl-5-methyl-cyclohexyl ester (4.75 g, 45%), d.e=99.8:0.2 (HPLC), as a white powder. forming a light yellow suspension The dropping funnel was washed with THF The emulsion was stirred for 105 minutes at room temperature Heptane (486 mL) was added within 40 minutes after 60 more minutes of stirring the precipitate was filtered off washed with heptane, water heptane in that order and dried under vacuum at 55° C.