Enantioselective olefin epoxidation using novel biphenyl and binaphthyl azepines and azepinium salts

Homologous biphenyl and (diastereomeric) binaphthyl tertiary azepines and quaternary iminium salts were prepared from (S)- and (R)-3,3-dimethylbutan-2-amine. Both the amines and iminium ions behave as effective catalysts for the enantioselective epoxidation of unfunctionalized olefins (ee up to 87%).

Figure optionsDownload as PowerPoint slide

(−)-(Ra)-4,5-Dihydro-3H-4-[(S)-3,3-dimethylbutan-2-yl]dinaphth[2,1-c;1′,2′-e]azepineC28H29NDe >99%[α]D20=-272.4 (c 0.10, MeOH)Source of chirality: (S)-1,2,2-trimethyl-propylamine, (Ra)-2,2′-bis(bromomethyl)-1,1′-binaphthyl made (Ra)-BINOLAbsolute configuration: (Ra,S)

(−)-(Ra)-4,5-Dihydro-3H-4-[(R)-3,3-dimethylbutan-2-yl]dinaphth[2,1-c;1′,2′-e]azepineC28H29NDe >99%[α]D20=-255.8 (c 0.10, MeOH)Source of chirality: (R)-1,2,2-trimethyl-propylamine, (Ra)-2,2′-bis(bromomethyl)-1,1′-binaphthyl made (Ra)-BINOLAbsolute configuration: (Ra,R)

(−)-(Ra)-[(S)-3,3-Dimethylbutan-2-yl]-3H-4-azapinium-cyclohepta[2,1-a;3,4-a′]dinaphthalene (rac)-TRISPHATC46H28Cl12NO6PDe >99%[α]D20=-207.4 (c 0.10, MeOH)Source of chirality: (S)-1,2,2-trimethyl-propylamine, (Ra)-2,2′-bis(bromomethyl)-1,1′-binaphthyl made (Ra)-BINOLAbsolute configuration: (Ra,S)

(−)-(Ra)-[(R)-3,3-Dimethylbutan-2-yl]-3H-4-azapinium-cyclohepta[2,1-a;3,4-a′]dinaphthalene (rac)-TRISPHATC46H28Cl12NO6PDe >99%[α]D20=-264.3 (c 0.10, MeOH)Source of chirality: (R)-1,2,2-trimethyl-propylamine, (Ra)-2,2′-bis(bromomethyl)-1,1′-binaphthyl made (Ra)-BINOLAbsolute configuration: (Ra,R)