methyl 2-sulfanylidenepiperidine-4-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Add Lawesson's reagent (9.2 g, 22.7 mmol) to a solution of methyl 2-oxopiperidine-4-carboxylate (6.5 g, 41.4 mmol) in toluene (83 mL) and heat to reflux for 2 hours. Cool the solution and concentrate to dryness under reduced pressure. Purify the residue by flash chromatography on silica gel, eluting with ethyl acetate:dichloromethane (gradient 5-15%) to afford the title compound (6.95 g). 1H NMR (CDCl3) δ 1.97 (m, 1H), 2.17 (m, 1H), 2.78 (m, 1H), 3.03 (m, 1H), 3.24 (m, 1H), 3.39 (m, 1H), 3.49 (m, 1H), 3.72 (s, 3H), 8.48 (bs, 1H). heat to reflux for 2 hours Cool the solution concentrate to dryness under reduced pressure Purify the residue by flash chromatography on silica gel eluting with ethyl acetate