For carbocyclic systems

Trivial names for carbocyclic systems cited in increasing order of preference for selection as base component in fusion names... 

ZC91). A related reaction, with even more curious consequence, is shown in equation (33) (73CJC839). However, aldol condensation of thiochromanones with aldehydes in the presence of weak bases proceeds exactly as for carbocyclic systems (79MI22501). 

Fitzsimmons, B J, Fraser-Reid, B, Annulated pyranosides as chiral synthons for carbocyclic systems. Enantiospecific routes to both (-1-)- and (—)-chrysanthemum dicarboxylic acids from a single progenitor, J. Am. Chem. Soc., 101, 6123-6125, 1979. 

The conformational behavior of 9-heterobicyclo[3.3.1]nonanes usually follows the regularities found for carbocyclic systems. For a series of 9-oxa derivatives 221-225, X-ray studies revealed the CC conformation in the solid state (167-171). The CC conformation was also found for salt 226 (from X-ray data) (172). 

A large field of applications of the HOMA index has recently been presented in two reviews [25,72], so there is no need to repeat them. The most important achievement is that the HOMA index can be analytically separated into two terms [26, 85] which account for the energetic and geometric contributions, EN and GEO, respectively. Originally this was done for carbocyclic systems [26], then the formula was modified to account for heterocyclic systems as well [85]. This more general formula is presented by eq. (13) ... 

When the cnolate of an enone is brought into reaction with an enone, usually a carbocyclic system is prepared by two consecutive Michael additions (M1MIRC reactions). Due to the lower temperatures employed and the absence of diene polymerization these reactions are useful alternatives for Diels-Alder reactions and proceed in general with high diastereoselectivities. When neither enolate nor enone is cyclic a monocyclic system is formed 338 which can be converted into a bicyclic system when the Michael addition is followed by an aldol reaction339. When, however, the enolate is cyclic a bicyclic or a tricyclic system is formed340 341. 

From the results we have obtained for the systems C,H4, Q,H6, and CKH8 we can infer a rule, first discovered by Huckel and now rather well known, concerning the aromaticity of planar, carbocyclic systems of the type (CH) . 

With these considerations in mind, the process of constructing the correct linear combinations of the subsets proceeds exactly as in the case of the carbocyclic systems. The correct coefficients of the atomic orbitals are simply the characters of the representations. For the E orbitals we will obtain some imaginary coefficients, but these may be eliminated by taking the appropriate linear combinations. We can thus write, almost by direct inspection of the character table of the C4 group ... 

The most recent recommendations by IUPAC for naming heterocyclic skeletons include only a small number of basic nomenclature systems, and, as a consequence of its need to provide unique names, the number of systems employed by Chemical Abstracts is even smaller. Of the systems now to be outlined, most are described in detail in the Appendix (to which reference is made where appropriate) the following text will cover only the general principles involved. Many of the systems are modifications of those used for carbocycles. 

In contrast, the closely related palladium acetate-promoted intramolecular alkylation of alkenes by tri-methylsilyl enol ethers (Scheme 4)6,7 has been used to synthesize a large number of bridged carbocyclic systems (Table 1). In principle, this process should be capable of being made catalytic in palladium(II), since silyl enol ethers are stable to a range of oxidants used to carry the Pd° -> Pd11 redox chemistry required for catalysis. In practice, catalytically efficient conditions have not yet been developed, and the reaction is usually carried out using a full equivalent of palladium(II) acetate. This chemistry has been used in the synthesis of quadrone (equation 2).8 With the more electrophilic palladium(II) trifluoroace-tate, methyl enol ethers underwent this cyclization process (equation 3).9... 

Finally, ring expansions of cyclic ketones are an important method for the preparation of carbocyclic systems. Diazoalkanes allow this reaction to occur and involve C—C bond formation. When combined with carefully chosen organoaluminum compounds, this process can be performed in a highly stereoselective fashion (equation 148)541. 

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