Cyclophanes, synthesis

STEPHENS CASTRO Acetylene cycloptiane synthesis Polyacetylene cyclophane synthesis from an iodophenyl copper acetylide... 

H. Takemura, M. Kotoku, M. Yasutake, T. Shinmyozu, 9-Fluoro-18-hydroxy-[3.3]meta-cyclophane Synthesis and estimation of a C-F---H-0 hydrogen bond, Eur. J. Org. Chem. 9 (2004) 2019-2024. 

Mjgtle, F. Cyclophanes Synthesis, Structures, and Reactions John Wiley Sons New York, 1993. 

Gabutti S, Schaffner S, Neuburger M, Fischer M, Schafer G, Mayor M (2009) Planar chiral asymmetric naphthalenediimide cyclophanes synthesis, characterization and tunable FRET properties. Org Biomol Chem 7 3222-3229... 

The pyrolytic elimination of sulfur dioxide from cyclic sulfones to give (strained) macrocycles (sulfone pyrolysis) counts among the most important reactions in cyclophane chemistry. There is hardly any research group dealing with cyclophanes which did not make use of the sulfone pyrolysis for the synthesis of such molecules. Since its first application in cyclophane synthesis over twenty years ago [1], the sulfone pyrolysis enabled researchers to synthesize a wealth of strained cyclophanes and developed into a reaction of general importance. 

STEPHENS CASTRO Acatyl necydopHanasynthesis Polyacstytene cyclophane synthesis from an lodophenyl copper aeetylide... 

Cyclophane synthesis necessarily involves the closure of medium- to large-sized rings and is therefore always problematic because of competing oligomerisation and polymerisation reactions. It is beyond the scope of this work to present a detailed treatment of the numerous procedures for preparing cyclophanes, but an excellent overview may be found in the key reference and literature. Some common techniques and particular tricks in this advanced form of organic synthesis are worth referring to, however, and a few important reactions in cyclophane (and macrocyclic) synthesis are listed below ... 

Another example of thermodynamic product control is found in the cyclophane synthesis reported by Okada et al. [131]. They found that irradiation of 135 yielded exclusively 136 (Scheme 55), which had both cyclobutane rings in the exo orientation. Calculations revealed that the bis-exo cycloadduct 137 had 12 kcal moT less strain energy than the bis-endo adduct 139 and 6 kcal mol less strain energy than the exo-endo compound 138 (see Fig. 3). With energy differences of this magnitude, the selectivity exhibited by this... 

The substantial amount of strain in [6]paracyclophane (la) (Structures 1) and its lower homologues precluded ordinary synthetic methods for cyclophane synthesis. Viable alternative should therefore be based on transformation from high energy species such as strained molecules or reactive intermediates like... 

Bridged [njcyclophanes of condensed benzenoid aromatics with n > 8 were prepared by the ordinary methods of cyclophane synthesis. These include [8]... 

In line with the immense structural diversity of cyclophanes, the synthetic approaches are extremely heteroge-neous and cannot be reviewed in a short synopsis. Progress in the preparation of cyclophanes is closely associated with the development of synthetic methodology for ring closure and ring contraction. Three principles of general importance in cyclophane synthesis should be mentioned. 

Keywords Cyclophane, Synthesis, Benzenoid Hydrocarbons, Arenes, Polyphenyls. 

Nishimura J, Nakamura Y, Hayashida Y, Kudo T (2000) Stereocontrol in cyclophane synthesis a photochemical method to overlap aromatic rings. Acc Chem Res 33(10) 679-686... 

Yamauchi Y, Fujita M (2010) Self-assembled cage as an endo-template for cyclophane synthesis. Chem Commun 46 5897-5899... 

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