Cyclophanes, nomenclature

Cyclopent-2-en-l-one, 2-hydroxy-3-methyl-synthesis, 3, 693 Cyclopentenone, 4-methoxy-formation, 1, 423 Cyclopenthiazide as diuretic, 1, 174 Cyclopent[2,3-d]isoxazol-4-one structure, 6, 975 Cyclophane conformation, 2, 115 photoelectron spectroscopy, 2, 140 [2,2]Cyclophane conformation, 2, 115 Cyclophanes nomenclature, 1, 27 Cyclophosphamide as pharmaceutical, 1, 157 reviews, 1, 496 Cyclopiloselloidin synthesis, 3, 743 Cyclopolymerization heterocycle-forming, 1, 292-293 6H-Cyclopropa[5a,6a]pyrazolo[l,5-a]pyrimidine pyrazoles from, 5, 285 Cydopropabenzopyran synthesis, 3, 700 Cyclopropachromenes synthesis, 3, 671 Cyclopropa[c]dnnolines synthesis, 7, 597 Cyclopropanation by carbenes... 

The calixarenes are a popular and versatile class of macrocycle formed from the condensation of a p-substituted phenol (e.g. p-tert-butylphenol) with formaldehyde. Since they contain bridged aromatic rings, they are formally members of the cyclophane family (Section 6.5). In cyclophane nomenclature they are termed substituted [l.l.l.ljmetacyclophanes . The descriptive name calixarene was coined by C. David Gutsche (Washington University, USA) because of the resemblance of the bowl-shaped conformation of the smaller calixarenes to a Greek vase called a calix crater (Figure 3.78). The number of phenolic residues is denoted by a number in square brackets. Thus the most common cyclic tetramer with p-f-butyl substituents is termed p-t-butyl-calix[4]arene (3.118). It is easy to understand why this appealing nomenclature has found wide acceptance within the field when it is compared to the Chemical Abstracts systematic name for 3.118, [19.3.1.U U l ]octacosa-l(25),3,5,7(28),9,ll,... 

Initially, the phane concept was intended solely for supercyclic systems, namely, cyclophanes. During elaboration of the new all-encompassing cyclophane nomenclature it became more and more obvious that its basic principles apply equally well to extended linear assemblies of chain and ring segments. Such superchains can then be treated exactly like cyclophanes, except that their names end with the morpheme... phane after the numerical term denoting the length of the superchain. 

The nomenclature of phanes is simple 32) It mainly defines the length(s) of the bridge(s) and their positions in the ring as illustrated by the following examples [6]para-cyclophane (2) 1,10-dioxa [10]paracyclophane (6), [2.2]paracyclophane (7), [2.2]meta-(8) and [2.2]metaparacyclophane (9) and [8](2,5)pyridinophane (70). The formulae show also the kind of projection used in this survey to illustrate stereochemical relations. 

A specialized system of nomenclature has been developed, principally by Smith,16 for naming skeletons consisting of aromatic residues linked in various ways by saturated bridges. Those skeletons containing benzene residues only are termed cyclophanes, and names for heteroaromatic analogues are based on the name of the heterocycle with the termination -ophane. The numbers of atoms in the bridges are indicated in square brackets, and the orientation of substitution on the aromatic residue(s) is shown in parentheses. A few simple examples are given (149-151), with alternative names. 

Figure 6.31 Application of the Vogtle/Neumann and IUPAC nomenclature for cyclophanes.

One of the main reasons why nodal nomenclature [42] was created was that the IUPAC organic nomenclature did not allow for assigning unique canonical names to members of the class of molecules referred to as "cyclophanes" a problem that would not have arisen had beta bonds been available. This is not to devalue the many virtues of nodal nomenclature, rather merely to show how the proposed system nomenclates these compounds without difficulty. 

For example, consider [2,3]-ortho,para-cyclophane (Figure 19). Before presenting the nomenclature assignment for this molecule, it is instructive to examine both the current traditional IUPAC "organic"... 

One of the main motivations for the development of nodal nomenclature was to be able to compensate for inadequacies that prevented the assignment of a consistent set of canonical names to selected, then recently formulated, molecules — especially the cyclophanes. 

Regarding the big family of enforced cavity hosts, a more specific nomenclature than class names is more or less in use only for the calixarenes and cyciodextrins. In case of the calixarenes. the number of phenolic residues is denoted by a number in square brackets.Thus, the most common cyclic tetramer with p-f-butyl substituents (Fig. 4h) is termed / -r-butyl-calix[4]arene. When using the cyclophane nomenclaturethe calix[4]arene would... 

Fig. 1 Selected cyclophane structures and their nomenclature according to Vdgtle/Neumann and to lUPAC ...

Figure 2.28 The cyclophanes, [2,2] metacyclophane (2.117a) and [2,2]paracyclophane (2.117b), showing the original (Vogtie and Neumann) and lUPAC nomenclatures.

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