Sulfuric Acid → (S)-1-(Trifluoroacetyl)piperazine-2-carboxylic acid tert-butylamide sulfuric acid salt

Participants

Reaction Steps

2.50 g (8.95 μmol) of 1-trifluoroacetyl-1,4,5,6-tetrahydropyrazine-2-carboxylic acid tert-butylamide, 7.5 mg (18 μmol) of bis(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate and 11.5 mg (21 μmol) of 1-[1(R)-(di-tert-butylphosphino)ethyl]-2-(S)-(diphenylphosphino)ferrocene were placed in a 50 ml autoclave under argon (educt:catalyst=486). A solution of 0.89 g (9.08 mmol) of sulfuric acid in 20 ml of degassed tetrahydrofuran was then added. Hydrogenation was then carried out for 18 hours at 200° C. under a hydrogen pressure of 13-10 bar. After distillation of the solvent, 3.42 g (>99%) of the title compound were obtained in the form of a white powder. After cleavage of the protecting groups, the enantioselectivity of the hydrogenation was determined by GC analysis, giving an ee of 79.5 percent. Other data concerning the title compound was:

Provenance & Evidence