Acetic Acid → 1,2-dibenzyl 1-tert.butyl 4-methyl-1-(4-pyrrolidinylbut-2-yn-1-yl)-1,1,2(R)-pentanetricarboxylate

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Reaction Steps

A mixture of 0.501 g of 1,2-dibenzyl 1-tert.butyl 4-methyl-1-(prop-2-yn-1-yl)-1,1,2(R)-pentanetricarboxylate, 0.17 ml of pyrrolidine, 0.083 g of paraformaldehyde, 0.39 ml of glacial acetic acid and 0.004 g of cuprous chloride in 7 ml of dioxan was stirred at room temperature under a nitrogen atmosphere for 15 minutes and then heated to reflux for 2 hours. The mixture was then stirred at room temperature for a further 2 hours and evaporated, and the residue was partitioned between water and dichloromethane. The pH of the aqueous phase was adjusted to 10 by the addition of ammonium hydroxide and the dichloromethane layer was separated. The aqueous phase was extracted with three portions of dichloromethane and the combined extracts were washed with water, dried over anhydrous magnesium sulfate and evaporated to give a brown oil which was purified by flash chromatography on silica gel using ethyl acetate/hexane (4:1) for the elution. There was obtained 0.489 g of 1,2-dibenzyl 1-tert.butyl 4-methyl-1-(4-pyrrolidinylbut-2-yn-1-yl)-1,1,2(R)-pentanetricarboxylate in the form of a colorless oil; MS 576 (M+H)+.

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