tert-Butyl 4-oxopiperidine-1-carboxylate → 1-tert-butoxycarbonyl-4-{4-[1 (S)-(4-bromophenyl)-ethyl]-3(R)-methylpiperazin-1-yl}-piperidine

Participants

Reaction Steps

The product of step 4 was stirred for 20 h. at RT with N-Boc-4-piperidinone (4.32 g), HOAC (1.15 ml), CH2Cl2 (80 ml) and sodium triacetoxy-borohydride (NaBH(OAc)3) (8.3 g). Thereafter the reaction was quenched with excess aqueous Na2CO3 solution slowly and stirred for 0.5 h. The organic layer was separated and filtered through a pad of silca gel, washing with 10:1 CH2Cl2-Et2O to elute all of the product. The filtate was evaporated and dissolved in Et2O (100 ml). To this was added dropwise a 4M solution of HCl in 1,4-dioxane (10 ml). The solids were collected, washed with Et2O, and stirred with CH2Cl2 and excess aqueous NaOH. The organic phase was dried over K2CO3 and evaporated to obtain 1-tert-butoxycarbonyl-4-{4-[1 (S)-(4-bromophenyl)-ethyl]-3(R)-methylpiperazin-1-yl}-piperidine (5.45 g).

Provenance & Evidence