Formaldehyde → phenylmethyl 4-methyloctahydro-1(2H)-quinoxalinecarboxylate

Participants

Reaction Steps

To a solution of phenylmethyl octahydro-1(2H)-quinoxalinecarboxylate (enantiomeric mixture) (2.32 g, 8.5 mmol) in dichloromethane (80 mL) at 0° C. was added formaldehyde (0.76 mL, 37% water solution, 10.2 mmol) followed by sodium triacetoxyborohydride (2.7 g, 12.75 mmol). The reaction mixture was allowed to warm to room temperature and stirred for 1 h before being diluted with dichloromethane and washed with 1N NaOH solution. The organics were washed with brine, dried (Na2SO4) and evaporated to yield 2.3 g of phenylmethyl 4-methyloctahydro-1(2H)-quinoxalinecarboxylate (enantiomeric mixture, cis) (2.3 g), which was separated by chiral LC to afford phenylmethyl (4aS,8aR)-4-methyloctahydro-1(2H)-quinoxalinecarboxylate, and phenylmethyl (4aR,8aS)-4-methyloctahydro-1(2H)-quinoxalinecarboxylate. Absolute configuration was assigned using Ab Initio vibrational circular dichroism. LCMS: (M+H)+: 289.2.

Provenance & Evidence