Triethylamine → Benzyl [7-{N-(tert-butoxycarbonyl)amino}-3-(3-methoxy-4-nitrobenzoyl)-2-methylindolizin-1-yl]carboxylate

Participants

Reaction Conditions

Reaction Steps

9.4 g (53.38 mmol) of benzyl crotonate, 1.8 mL (12.8 mmol) of triethylamine and 3.7 g (42.68 mmol) of manganese oxide are successively added to a solution of 5.0 g (10.67 mmol) of 4-[N-(tert-butoxycarbonyl)amino]-1-[2-(3-methoxy-4-nitrophenyl)-2-oxoethyl]pyridinium bromide in 40 mL of dimethylformamide. The reaction mixture is then heated at 90° C. for 4 hours and then filtered on a silica bed, eluting with ethyl acetate. The filtrate is poured over water and extracted with ethyl acetate. After decantation, the organic phase is washed with a saturated sodium chloride solution, dried over sodium sulfate and then concentrated under reduced pressure. The product is purified by chromatography on silica gel, eluting with a toluene/ethyl acetate (95/5 to 70/30) mixture. 2.6 g of an orange-coloured powder are obtained.

Provenance & Evidence