HCID 58928407, compound → HCID 58928364, compound

Participants

Reaction Conditions

Reaction Steps

(6R,9aS)-2-benzyl-6-(4-methoxy-2,3-dimethylphenyl)-octahydro-pyrido[1,2-a]pyrazin-8-one (9.48 g, 25.0 mmol) is stirred with p-toluenesulfonyl hydrazide (5.60 g, 30.0 mmol, 1.2 eq) in 40 mL anhydrous THF and 200 mL anhydrous MeOH for 20 h at ambient temperature under a nitrogen atmosphere. LC/MS analysis indicates complete conversion to the p-toluenesulfonyl hydrazone. The solution is sparged with argon for 30 min and then treated with 50 mL of a 1.5 M solution of NaCNBH3 in MeOH. Zinc trifluoromethanesulfonate (140 mg, 0.376 mmoles, 1.5%) is added and the solution is heated in a 65° C. oil bath for 5.5 h under an argon balloon. LC/MS analysis indicates consumption of the hydrazone. The mixture is allowed to cool and is quenched with 500 mL of saturated NaHCO3. After stirring vigorously for 30 min, the mixture is extracted with CH2Cl2 (4×200 mL). The combined extracts are dried over Na2SO4, filtered and concentrated in vacuo. The residue is purified by column chromatography on silica gel eluting with 90%-80% hexanes/EtOAc to yield (6R,9aS)-2-Benzyl-6-(4-methoxy-2,3-dimethylphenyl)-octahydro-pyrido[1,2-a]pyrazine as an oil. LC/MS: 365 (M+1). 1H NMR (400 MHz, CDCl3): 7.34 (1H, d), 7.27 (5H, m), 6.72 (1H, d), 3.79 (3H, s), 3.47 (2H, dd), 3.28 (1H, d), 2.68 (3H, m), 2.28-2.04 (8H, bm), 1.98-1.88 (2H, bm), 1.75 (1H, m), 1.59 (1H, d), 1.50-1.30 (4H, bm).

Provenance & Evidence