Synthesis of polymer intermediates containing the bicyclo[3.2.2]nonane ring

Abstract

The preparation of 1,5-biscarbethoxybicyclo[3.2.2]nonane and 1,5-bis(hydroxymethyl)bicyclo[3.2.2]nonane is described. The procedure generally followed that reported for the analogous bicyclo[2.2.2]octanes. However, certain differences in chemical behavior were observed and are reported.The alkylation of the sodium salt of diethyl succinylsuccinate produced the expected 1,5-biscarbethoxybicyclo[3.2.2]nonane-6,8-dione along with a by-product which was shown to be 1,5-biscarbethoxybicyclo[4.2.1]nonane-7,9-dione. It was also shown that this compound arose by isomerization of the bicyclo[3.2.2]nonane analogue after the alkylation occurred.Conversion of these compounds to thioketals with 1,3-propanedithiol was also examined in detail. The reaction between 1,3-propanedithiol and 1,5-biscarbethoxybicyclo[3.2.2]nonane-6,8-dione generated an equilibrating system of 4 compounds. Three of these are shown to be the monothioketal, the bisthioketal, and a mixed thioketal–vinylthioether.