5-Hexenal → 5-(Hex-5-enyl)-2,3-dip-tolyl-5,6,7,8-tetrahydropyrido[2,3-b]pyrazine

Participants

Reaction Steps

Hex-5-enal (step 1) (solution in DCM, 25 mmol) was treated with 2,3-di-p-tolyl-5,6,7,8-tetrahydropyrido[2,3-b]pyrazine (Intermediate B) (3.94 g, 12.5 mmol). After stirring at room temp under nitrogen for 30 mins, sodium triacetoxyborohydride (3.18 g, 15.00 mmol) was added and stirring continued at room temperature overnight. Water (100 ml) was added to the reaction mixture. Once effervescence had ceased the organic portion was separated and dried by passing through a phase separating column. The solvent was removed under reduced pressure and the resulting brown oil was purified by flash column chromatography on silica eluting with 0-100% EtOAc in iso-hexane on a 80 g silca cartridge. The combined fractions were allowed to stand at room temperature for 2 days. The resulting suspension was collected by filtration and dried in a vacuum oven. The crude material was purified by chromatography on silica eluting with 0-50% EtOAc in iso-hexane to afford the title compound;

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