The Grignard condensation of oxalic acid dimethyl ester (I) with 2-thienylmagnesium bromide (II) gives 2-hydroxy-2,2-bis(2-thienyl)acetic acid methyl ester (III), which is submitted to transesterification with scopine (IV) catalyzed by Na or NaOEt, providing the corresponding ester (V). Finally, (V) is quaternized with methyl bromide in dichloromethane/acetonitrile.
The transesterification of 2-hydroxy-2,2-bis(2-thienyl)acetic acid methyl ester (I) with endo-8-methyl-8-azabicyclo[3,2,1]-6-octen-3-ol (II) gives the corresponding ester (III), which is epoxidated with V2O5 and H2O2 to yield the epoxy compound (IV). Finally, this compound is quaternized with methyl bromide as usual.