Synthesis of Bicyclo(5.3.1)Undec-1(11)-Ene and Bicyclo(3.3.1)Non-1(9)-Ene.

Abstract

In an effort to study the limits of Bredt's rule, bicyclo{5.3.1}undec-1(11)-ene and bicyclo{3.3.1}non-1(9)-ene were synthesized. In the preparation of bicyclo{5.3.1}undec-1(11)-ene, 11-oxobicyclo{5.3.1}undecane was reduced by lithium aluminum hydride to give a single isomer of 11-hydroxybicyclo{5.3.1}undecane. 11-Hydroxybicyclo{5.3.1}undecane was converted to the corresponding methanesulfonate ester, which, when treated with a solution of potassium tert-butoxide in refluxing tert-butyl alcohol, gave a 6.5% yield of bicyclo{5.3.1}undec-1(11)-ene. Reaction of 11-methanesulfonoxybicyclo{5.3.1}undecane with sodium iodide in acetone gave two isomeric 11-iodobicyclo{5.3.1}undecanes, which gave bicyclo{5.3.1}undec-1(11)-ene in 37% yield upon reaction with potassium tert-butoxide in refluxing tert-butyl alcohol. Bicyclo{5.3.1}undec-1(11)-ene was hydrogenated to give bicyclo{5.3.1}undecane. Chemical degradation of bicyclo{5.3.1}undec-1(11)-ene with potassium permanganate and sodium periodate followed by methylation with diazomethane gave 5-carbomethoxycyclodecanone, identical to the same compound obtained by an alternative route. In the synthesis of bicyclo{3.3.1}non-1(9)-ene, bicyclo{3.3.0}octane-1-carbinol was oxidized to bicyclo{3.3.0}octane-1-carboxaldehyde using pyridinium chlorochromate. The aldehyde was converted into the corresponding hydrazone, which upon reaction with iodine and triethylamine gave 1,9-diiodobicyclo{3.3.1}nonane and 1-(diiodomethyl)bicyclo{3.3.0}octane. Reaction of 1,9-diiodobicyclo{3.3.1}nonane with alkyllithium reagents at -78(DEGREES)C yielded dimers of bicyclo{3.3.1}non-1(9)-ene. Diels-Alder adducts were obtained in low yield when furan and butadiene were used as solvents in the reaction of 1,9-diiodobicyclo{3.3.1}nonane with alkyllithium reagents.