Butanedione → 3-Hydroxy-3-phenylbutan-2-one
Reaction equation
[C:1]1([Mg]Br)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[CH3:9][C:10](=[O:14])[C:11](=[O:13])[CH3:12]>C1COCC1.C1(C)C=CC=CC=1>[OH:14][C:10]([C:1]1[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1)([CH3:9])[C:11](=[O:13])[CH3:12]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
The process can also be run in mixtures of tetrahydrofuran and toluene, thereby making the process more economical. When 1.1 equivalent of phenylmagnesium bromide (1.9M in 50% THF/PhMe) was added to 2,3-butanedione in 50% THF/PhMe, crude product was isolated in 82.4% yield (Run 10, Table IV) after work-up. Short path vacuum distillation gave 3-hydroxy-3-phenylbutan-2-one in 68% yield. Alternatively, preparation of phenylmagnesium bromide in 38% THF/PhMe, followed by reaction with 2,3-butanedione in 38% THF/PhMe afforded 3-hydroxy-3-phenylbutan-2-one in 66.4% yield (Run 11, Table IV) after work-up and distillation. Similarly phenylmagnessium bromide in 25% THR/PheMe reacted with 2,3-butanedione in 25% THF/PheMe yielded 3-hydroxy-3-phenylbutan-2-one in 56.9% yield after work-up and distillation.