A new approach to all—cis triquinane synthesis and a new route to the C16—hexaquinane system

A new synthesis of all-cis triquinanes is presented. The examples bear a cis substituent on the fifth position of the central ring, and are thus all-cis pentasubstituted cyclopentanes. The stereo-controlled addition of organometallics of 7-ketonorbornenes is considered, as is “reductive solvolysis” of such adducts to the corresponding hydrocarbons. The preparation of trans-3,4-dimethoxycyclopentyl chloride is given, as is that of the corresponding organolithium. The use of quinoxaline derivatives in aldol-type reactions is considered, with examples. A new approach to the C₁₆-hexaquinane system is developed. The ring systems reported include: tricyclo-[8.2.1.0^2,9]tridecane, tricyclo[6.3.0.0^3,7]undecane, tetracyclo-[10.1.0.0^2,9.0^10,13]tridecane, pentacyclo[8.5.1.0^2,6.0^7,16.0^11,15]hexadene and hexacyclo(8.5.1.0^2,6.0^3,14.0^7,16.0^11,15]hexadecane.