7 beta-substituted 6a, 14a-ethenomorphinans and 7beta-substituted 6a, 14a-ethanomorphinans

The application is directed to a process for increasing the proportion of 7β-epimer in an 7α/7β-epimer mixture of a 7-substituted 6α,14α-ethenomorphinan or a 7-substituted 6α,14α-ethanomorphinan, and specifically of compounds of Formula (I), wherein G, R 2 -R 4 , and are defined as set forth in the specification. The application is also directed to a process for purifying the 7β-epimer from an 7α/7β-epimer mixture of a 7-substituted 6α,14α-ethenomorphinan or a 7-substituted 6α,14α-ethanomorphinan. The application is also directed to a process for preparing 7β-substituted compounds of Formula V b wherein G and R 2 -R 5 are defined as set forth in the specification.