M-Cyclophanes

The aryl groups of the styryl systems need not be unsubstituted, as has been illustrated before for the cyclizations encountered in the synthesis of naphthalenophanes from 120. Indeed cyclization to afford a cyclobutane derivative where methoxy groups are on the adjacent ring position to the vinyl moieties has also been studied. The irradiation of 138 affords the m-cyclophanes 139 and 14065. Further study has sought to evaluate the steric effect of o-methoxy groups in such molecules66. 

H. Plenio, J. Hermann, R. Diodone, The coordination chemistry of fluorocarbons Difluoro-m-cyclophane-based fluorocryptands and their group I and II metal ion complexes, Inorg. Chem. 36 (1997) 5722-5729. 

Cram, D. J. Cram, J. M. Cyclophane Chemistry Bent and Battered Benzene Rings. 

The m-cyclophanes 64-67 described by Pascal are excellent vehicles for the study of functional group interactions resulting from enforced pro-... 

Fig. 2 Examples of Four-component (ABC2) synthesis of m-cyclophanes...

Aromatic protons are strongly deshielded by the ring s tt orbitals, but protons that lie over the face of a ring are shielded. Use SpartanView to examine the structure of m-cyclophane, and assign the aromatic proton peaks in the H NMR spectrum 5 4.27,6.97, and 7.24 in a 1 2 1 ratio. 

Di-Grignard reagents couple with m-dichlorobenzene to form m-cyclophanes in one step but in up to 20% yields depending on the chain lengths oxamethylene bridges can also be introduced (equations 95 and 96). ... 

Based on this novel three-component synthesis of 5-aminooxazoles and by designing reaction partners, a two-fold four-component (ABC2) synthesis of m-cyclophane 21 was devised by reacting a diamine (22), a bis-a-isocyanoacetamide... 

When the 1,3-dielectrophile is part of a macrocycle, the cycloaromatization reaction can be used as a synthesis of m-cyclophanes as illustrated in Scheme 49.156... 

An interesting aspect of aromaticity is its relation to the planarity of the n-electron system in question. As it was shown using the geometry of m-cyclophane [94] and of per-substituted naphthalenes, even a substantial folding of the ring in the former case or of the bicyclic system in the latter, does not lead to the loss of aromatic character. It happens rather suddenly when a considerable deviation from coplanarity... 

Transannular cyclization. m-Cyclophane-lactams undergo oxidative cyclization. Certain members give indoles. 

Light transforms the dihydropyrene into the isomeric m-cyclophane, but in the dark the reverse process readily ensues to regenerate the thermodynamically more stable dihydropyrene [221,224] ... 

Cram, D.J. and Cram, J.M., Cyclophane chemistry bent and battered benzene rings, Acc. Chem. Soc., 4, 204, 1971 and references cited therein. 

The preparation of m-cyclophanes is possible through a combination of inter- and intramolecular S[y l substitutions with substrates bearing the leaving group and nucleophilic center in the same molecule Eq. (47.44)."3> ... 

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