Nucleophilic Substitution in the Allylic System of Codeine and Pseudocodeine: Reactions with lithium cyano(methyl)‐and (aryl)cyanocuprates. Crystal and molecular structure of 8α‐phenyl‐6,7‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan and 6α‐phenyl‐7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan

Nucleophilic substitution of 6β‐chloro‐7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan ( 1 ) and 8α‐bromo‐6,7‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan ( 2 ) with lithium cyano(methyl)‐ and (aryl)cyanocuprates(I) ( 5a–c ) was accompanied by allylic rearrangement with both change and retention of orientation of the substituting group ( Scheme 1, Table 1 ). Nucleophilic substitution in 7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan‐6α‐yl methanesulfonate ( 3 ) and 7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan‐6β‐yl methanesulfonate ( 4 ) proceeded without allylic rearrangement with both change and retention of the orientation of the substituting group ( Scheme 2, Table 1 ). X‐Ray diffraction studies of the products 6,7‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methyl‐8α‐phenylmorphinan ( 6b ) and 7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methyl‐6β‐phenylmorphinan ( 7b ) were carried out ( Figs. 1 and 2 ).