Useful Synthetic Routes to Pureexo-5-Vinyl-2-norbornene andendo-5-Vinyl-2-norbornene

Abstract Hydroboration of 5-vinyl-2-norbornene (1) with 9-BBN mainly affords 5-(2-hydroxyethyl)-2-norbornene (2). The iodo ether cyclization of 2 can convert only endo-5-(2-hydroxyethyl)-2-norbornene (2b) to iodo ether 10, followed by reductive elimination and subsequent dehydration to furnish endo-5-vinyl-2-norbornene (1b) which has not been isolated in pure form. Meanwhile, unreacted exo-5-(2-hydroxyethyl)-2-norbornene (2a) produces exo-5-vinyl-2-norbornene (1a) via dehydration.