Chapter 53 - Compounds with Seven-Membered and Larger Rings possessing One or More Unusual Hetero Atoms

Abstract

Publisher Summary General methods for the synthesis of compounds having larger rings containing unusual hetero atoms are the same or at least bear some resemblance to those available for five- and six-membered ring compounds. Addition of dioxane to solutions of alkanedi(magnesium bromides) in tetrahydrofuran yields solutions containing monomeric species, which on the basis of chemical evidence and conductivity measurements, are considered to be magnesiacycloalkanes. Dimercuracycloalkanes are not well-characterized compounds; they have been reported as products from the direct interaction of mercury and α,ω-dilithioalkanes in ether at fairly low temperatures. Hydroboration studies have demonstrated the formation of saturated, seven-membered, boron-containing rings, on the basis of their oxidation under alkaline conditions to alkane-l,6-diols. These include the borepins, unsaturated systems containing boron and borepanes, saturated systems containing boron. For the most part, unsaturated ring systems containing Group IV metalloidal elements (silicon, germanium, tin and lead) in seven-membered or larger rings, are obtained by halogenation and dehydrohalogenation of analogous saturated systems. Seven-membered and larger ring systems containing one or more atoms of Group V elements (higher than nitrogen) appear to be known only for phosphorus and arsenic. Polycyclic compounds containing iodine in 7- and 8-membered rings are prepared by methods used to obtain the analogous 5-and 6-membered ring compounds.