E. Butkus et al., Intramolecular ring closure via ether bond in reaction of alpha,alpha ' halogeno bicyclo[3.3.1]nonanediones under basic conditions, J CHEM S P1, (11), 1999, pp. 1431-1436
The stereoselectivity of halogenation of bicyclo[3.3.1]nonan-2-one 1 and bi
cyclo[3.3.1]nonane-2,6-dione 2 with molecular bromine and chlorine was stud
ied. The transformation of alpha-bromo- and chloro-bicyclo[3.3.1]nonanones
3-5 under Favorskii reaction conditions was studied. The reaction of alpha,
alpha'-dihalogeno diones in the presence of sodium methoxide, ethoxide, pro
poxide and potassium cyanide led to the intramolecular ring closure via C-O
bond formation giving the highly functionalized chiral 2-oxatricyclo[4.3.1
.0(3,8)]decane (2-oxaprotoadamantane) structure. Enantiomers of this cage s
tructure were resolved by chiral GLC. The intramolecular ring closure pathw
ay involving the intermediate alkoxybicyclo[3.3.1]nonanolate structure was
proposed.