Carbocydic ring system

A broad variety of special aldehydes and ketones are easily accessible by Heck-type reactions with allylic alcohols and their homologs [3]. The potential for the synthesis of carbocydic structures is illustrated by the macrocyde 11 [4] which obviously is the product of a fourfold Heck reaction (Scheme 3). A domino process consisting of a double Heck reaction followed by an intramolecular Aldol condensation leads to the annulated ring system 15 [5]. 

Unlike carbocydic and oxygen-containing heterocyclic systems, catalytic enantioselective synthesis of eight-membered ring amines not only proceeds efficiently and with excellent enantioselectivity, it can be carried out in the absence of solvent. Representative data regarding catalytic enantioselective synthesis of various N-containing heterocycles without the use of solvent is depicted in Scheme 11. This remarkably efficient and enantioselective... 

The most important 10ft carbocydic system is naphthalene (19) in which two benzene rings are fused together. The fused systems anthracene (20) and phenanthrene (21) obey Hiickd s rule, where n = 3, and have 14ft-electrons. All three compounds are typically aromatic and their chemistry is similar to that of benzene, as discussed in Chapter 12. 

The oxygen, since it must be attached to two carbon atoms (in order that it be an ether), can be incorporated into a ring otherwise made up of carbon (or other) atoms. In this way, members of oxygen containing heterocydes, corresponding to the similar carbocydes encountered earlier (Chapter 4) can be made up. Regrettably, no simple system of nomenclature has been developed to deal with these ethers and trivial names are commonly used. 

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