Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Acid promoted cyclisation of homochiral (R)-N-(3,4-dimethoxyphenethyl)-halostachine proceeds with almost total racemisation to yield 1-phenyl-N-methyl-1,2,4,5-tetrahydrobenz[d]azepine (e.e. 6%). Coordination of the cyclisation precursor to the tricarbonylchromium(0) moiety renders the cyclisation completely stereospecific to afford, after decomplexation, homochiral (+)-(R)-1 -phenyl-N-methyl-1,2,4,5-tetrahydrobenz[d]azepine. (-)-(1R,2S)-N-(3,4-Dimethoxyphenethyl)ephedrine undergoes acid mediated cyclisation to furnish trans-(-)-(1R,2S)-1-phenyl-2-methyl-N-methyl-7,8-dimethoxy tetrahydrobenzazepine as a single diastereoisomer. In contrast, the epimeric cyclisation precursor (-)-(1R,2R)-N-(3,4-dimethoxyphenethyl)pseudoephedrine cyclises to give a mixture (ratio 91:9) of trans- and cis-1-phenyl-2-methyl-N-methyl-7,8-dimethoxy tetrahydrobenzazepine. However, cyclisation of the tricarbonylchromium(0) complex of(-)-(1R,2R)-N-(3,4-dimethoxyphenethyl)pseudo-ephedrine is completely stercoselective to yield trans-(+)-(1S,2R)-1-phenyl-2-methyl-N-methyl-7,8-dimethoxy tetrahydrobenzazepine after decomplexation. © 1991.

Original publication




Journal article


Tetrahedron: Asymmetry

Publication Date





33 - 56