Dimethyl Sulfoxide → 7-((R)-2-formyl-6-oxo-piperidin-1-yl)-hept-5-enoic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

7-((R)-2-Hydroxymethyl-6-oxo-piperidin-1-yl)-hept-5-enoic Acid Methyl ester 95% Ethanol (0.5 mL) was added to a mixture of nickel (II) chloride (105 mg, 0.81 mmol) and sodium borohydride (15 mg, 0.40 mmol). The mixture immediately turned black. After 15 min at rt, ethylene diamine (86 μL, 1.29 mmol) was added. After 15 min at rt, a solution of 7-((R)-2-hydroxymethyl-6-oxo-piperidin-1-yl)-hept-5-ynoic acid methyl ester (from Example 1, step 3, 43.3 mg, 0.16 mmol) in 95% ethanol (1.0 mL) was added via cannula. A hydrogen atmosphere was established by evacuating and refilling with hydrogen (3×) and the reaction mixture was stirred under a balloon of hydrogen for 19 h. The reaction mixture was filtered through celite, washing with ethanol, and the filtrate was concentrated in vacuo. Purification of the residue by flash column chromatography on silica gel (CH2Cl2→3% MeOH/CH2Cl2, gradient) afforded 16.7 mg (38%) of 7-((R)-2-hydroxymethyl-6-oxo-piperidin-1-yl)-hept-5-enoic acid methyl ester. Step 2. 7-((R)-2-Formyl-6-oxo-piperidin-1-yl)-hept-5-enoic acid methyl ester EDCI (36 mg, 0.19 mmol) and DMSO (18 μL, 0.25 mmol) were added sequentially to a solution of 7-((R)-2-hydroxymethyl-6-oxo-piperidin-1-yl)-hept-5-enoic acid methyl ester (16.7 mg, 0.062 mmol) in benzene (1.0 mL) at rt. The mixture was cooled to 0° C. and pyridinium trifluoroacetate (13.2 mg, 0.068 mmol) was added. The reaction was allowed to warm to rt and then was stirred at rt for 2.5 h. The solution was decanted from the oily residue and the residue was washed with benzene (3×1 mL). The combined benzene phases were concentrated in vacuo to afford crude 7-((R)-2-formyl-6-oxo-piperidin-1-yl)-hept-5-enoic acid methyl ester that was used without further purification.

Provenance & Evidence