Oxygen → (R)-2-(6-Cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4yl)-pyridine 1-oxide

Reaktionsgleichung

[C:1]([C:3]1[CH:4]=[CH:5][C:6]2[O:11][C:10]([CH3:13])([CH3:12])[CH:9]=[C:8]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][N+:15]=3[O-:20])[C:7]=2[CH:21]=1)#[N:2].C1(C)C=CC=CC=1.O=O>ClCCl>[C:1]([C:3]1[CH:4]=[CH:5][C:6]2[O:11][C:10]([CH3:13])([CH3:12])[CH2:9][C@@H:8]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][N+:15]=3[O-:20])[C:7]=2[CH:21]=1)#[N:2]

Komponenten

Versuchsvorschrift

100 mg (359 mmol) of 2-(6-cyano-2,2-dimethyl-2H-1-benzopyran-4-yl)pyridine 1-oxide, 9 ml of toluene, 1 ml of dichloromethane, 5.8 mg (14.4 mmol) of [Rh(COD)2 ]BF4 and 6.1 mg (14,4 mmol) of (R)-BIPHAS were placed in a 30 ml autoclave in a glove box (O2 content <1 ppm). The autoclave was sealed and the hydrogenation was carried out at 40° while stirring and a pressure of 40 bar. The hydrogenation was interrupted after 20 h. In order to determine the e.e. value and the conversion, a sample of the hydrogenation solution was evaporated and analyzed by HPLC on a chiral phase (Chiralcel OD-H). (R)-2-(6-Cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4yl)-pyridine 1-oxide was obtained in quantitative yield: e.e.=85%; chem. purity >99%.