3-Bromobenzaldehyde → 3-(4-Piperidin-1-yl-but-1-ynyl)-benzaldehyde

Participants

Reaction Conditions

Reaction Steps

To the mixture of Pd(PPh3)Cl2 (24 mg, 0.034 mmol, 0.02 equiv.), CuI (13 mg, 0.068 mmol, 0.04 equiv.) and 3-bromobenzaldehyde (0.316 g, 1.7 mmol, 1 equiv.), pyrrolidine (10 mL) were added under N2. The use of pyrrolidine is preferred in the context of this synthesis. A stream of N2 was bubbled into to the solution for 5 min, and then 1-but-3-ynyl-piperidine (0.46 g, 3.3 mmol, 2 equiv.) was added. The reaction mixture was stirred at 50° C. for 40 h. This temperature is preferred in the context of this synthesis. On TLC and HPLC, the reaction was complete. The white precipitate (Et3N.HBr) was filtered and washed with EtOAc. The solvent was evaporated and the residue was re-dissolved in EtOAc. The organic layer was washed with aqueous NaOH (1N) twice, and dried over MgSO4. After filtration, the EtOAc solution was poured directly onto a short pad of silica gel (neutralized with 5% Et3N in hexanes) and washed with EtOAc. The solvent was evaporated to afford the product as a brown oil (0.35 g, 1.45 mmol, 86%); purity >95% on HPLC; MS M+H+242. This product does not need further purification in its use for subsequent steps in the context of this invention. A yield of 86% is in marked contrast with conventional methodologies, which produce the title compound with typical yields that do not exceed 30%.

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