An enantioselective synthesis of a 6,7-bentzomorphan through the cyclisation of the chromium tricarbonyl complex of an 1-(aminoethan-2′-yl)- 1,2-dihydronaphthalene

Abstract

(−)1( S),2( S),4( R),6( R)-1,2,3,4,5,6-Hexahydro-2,6-methano-8-methoxy- 1,3,4,6-tetramethyl-3-benzazocine has been synthesised in 86 % enantiomeric excess from the α-(η 6-chromium tricarbonyl) complex of 1 ( S), 1′( R)- 1,2-dihydro-7-methoxy- 1,4-dimethyl - 1 -( N-methylN-trifluoroacetamido- 1′-methylethan-2′-yl)naphthalene. A precursor of this compound is 2( R),4( S)-4-(3-methoxyphenyl)-2,4-dimethylcyclohexanone which was obtained through an Enders' type C-methylation reaction of 4-(3-methoxyphenyl)4-methylcyclohexanone using SAMP as the reagent.