Benzaldehyde → 1,2-Diphenylpentane-1,4-dione

Reaction equation

[CH:1](=[O:8])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[C-]#N.[Na+].[C:12]1(/[CH:18]=[CH:19]/[C:20](=[O:22])[CH3:21])[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1>CN(C=O)C>[C:2]1([C:1](=[O:8])[CH:18]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)[CH2:19][C:20](=[O:22])[CH3:21])[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

Procedure

A solution of benzaldehyde (10.10 ml, 100 mmol) in DMF (50 ml) was added dropwise in the course of ½ hour to a mixture of sodium cyanide (2.450 g, 50 mmol) in DMF (50 ml) at 35° C. Stirring was continued for 1.5 hours at 35° C. A solution of (E)-4-phenylbut-3-en-2-one (10.9 g, 74.6 mmol) in DMF (50 ml) was slowly added dropwise over the course of 1.5 hours at 35° C. Stirring was continued for 3.5 hours at the same temperature. The reaction was quenched with twice its quantity of water and extracted with DCM, combined extracts were washed with water and brine, dried over Na2SO4, filtered and concentrated to give a liquid residue. This was purified by chromatography on silica gel using an automated Biotage system and EtOAc/Hexanes, 0-50%, to give 1,2-diphenylpentane-1,4-dione (7.3 g, 28.9 mmol, 38.8% yield). 1H NMR (400 MHz, CDCl3) δ (ppm) 7.97-7.94 (m, 2H), 7.49-7.49 (m, 1H), 7.39-7.35 (m, 2H), 7.29-7.20 (m, 5H), 5.10 (dd, 1H), 3.61 (dd, 1H), 2.75 (dd, 1H), 2.19 (s, 3H).