ABSTRACT
The asymmetric ruthenium-catalyzed reductive amination employing ammonia and hydrogen to primary amines is described. Here we demonstrate the capability of our catalyst to perform a chemo- and enantioselective process while using simple ammonia gas as a reagent, one of the most attractive and industrially relevant nitrogen sources. The presence of a catalytic amount of ammonium iodide was essential for obtaining good yields and enantioselectivities. The mechanism of this reaction was investigated by DFT and we found a viable pathway that also explains the trend and magnitude of enantioselectivity through the halide series in good agreement with the experimental data. The in-depth investigation of substrate conformers during the reaction turned out to be crucial in obtaining an accurate prediction of the enantioselectivity. Furthermore, we report the crystallographic data of the chiral [Ru(I)H(CO)((S,S)-f-binaphane)(PPh3)] complex, which we identified as the most efficient catalyst in our investigation.
ABSTRACT
An enantioselective hydrogenation of disubstituted furans has been developed by using a chiral ruthenium catalyst with N-heterocyclic carbene ligands. This reaction converts furans into valuable enantioenriched disubstituted tetrahydrofurans.
Subject(s)
Furans/chemistry , Catalysis , Heterocyclic Compounds/chemistry , Hydrogenation , Methane/analogs & derivatives , Methane/chemistry , Pressure , Ruthenium/chemistry , Solvents/chemistry , Stereoisomerism , TemperatureABSTRACT
cis-(3R)-(9-anthryl) derivative of cyclohexanol was conveniently obtained in enantiomerically pure form from 2-cyclohexenone using asymmetric Michael addition of anthrone catalyzed by l-proline in a key step. The absolute configuration of the addition product was unequivocally determined by means of electronic circular dichroism measurements combined with calculation of the circular dichroism spectrum by using a density functional theory method.
