Rotational isomerisum in fluorene derivatives XXIII syntheses of 1-substituted 1'-methyl-9, 9'-bifluorenyl derivatives and their conformational isomerisum

Rotational isomerisum in fluorene derivatives XXIII syntheses of 1-substituted 1'-methyl-9, 9'-bifluorenyl derivatives and their conformational isomerisum

Creators Nishida Akiko

Creators Nishiyama Shinichi

Creators Fujisaki Shizuo

Creators Kajigaeshi Shoji

The reaction of 1-substituted fluorenones (1-substituents: CH_3, F, Cl, Br, I, OCH_3, and Ph) with 1-methyl-9-fluorenyllithium gave a mixture of A (erythro) and B (threo)-isomers of 1-substituted 9-hydroxy-1'-methyl-9, 9'-bifluorenyls (2). In these cases, 2-B-isomers were obtained more abundantly than 2-A-isomers owing to the steric effects between 1-substituents and 1'-CH_3 group. 1-Substituted 1'-methyl-9, 9'-bifluorenyls (3) were prepared from the reduction of 2 with HI (method i) or the reaction of 9-bromo-1-methylfluorene with 1-substituted 9-fluorenyllithium (method ii). In these cases, 3-B-isomers were mainly obtained by method ii, whereas, 3-A-isomers by method i. Furthermore, the restricted rotation about the C(9)-C(9') bonds in 3 were investigated by DNMR method, and we could observe some rocking motion from one gauche form (a) to the other (e) in A-isomers of 1.1'-dimethyl-9, 9'-bifluorenyl (3a) and 1-fluoro-1'-methyl-9, 9'-bifluorenyl (3b).

[ISSN]0386-3433

[NCID]AA0086073X