4,15-Diamino[2.2]paracyclophane, a Reusable Template for Topochemical Reaction Control in Solution

Abstract

An efficient synthesis of [2.2]paracyclophane-4,15-dicarboxylic acid (11) from [2.2]paracyclophane (8) has been developed. The diacid was converted via the diazide 14 into the 4,15-diisocyanato[2.2]paracyclophane (15), a versatile intermediate that could be transformed into many new pseudogeminally substituted derivatives of 8. For example, treatment of 15 with alcohols provided the carbamates 16 and 17. On treatment of 15 with diisopropylamine, the urea 18 was obtained, whereas reduction with lithium aluminium hydride afforded the cyclic urea 20. Hydrolysis of 15 furnished the

Templating Photoreactions in Solution

“…Though not strictly homogeneous (chemical and photochemical transformations of the functionalized cross -linked polymers took place as dispersed solids in solution), the underlying principle is akin to the more recent use by Hopf and coworkers of a cyclophane -diamine to tether two cinnamate moieties in a geometry that is specifi c for the formation of the cis head -to -head (HH) dimer. 8 Hydrolysis of the amide linker allows nearly quantitative recovery of the β -truxinic acid photoproduct and the template.…”

“…24 Many of the photoinduced dimerization reactions described above for CDs have also been investigated using CBs and CAs as hosts, which can form the basis for useful comparisons. For example, 4,4 ′ -diaminostilbene forms 2:1 inclusion compounds in CB [8] hosts when deprotonated. Irradiation of this assembly leads to the exclusive formation ( > 95:5) of the cis photodimer, 25 analogously to what is observed for related E -3 in γ -CD.…”

“…Irradiation of this assembly leads to the exclusive formation ( > 95:5) of the cis photodimer, 25 analogously to what is observed for related E -3 in γ -CD. Irradiation of cinnamates 8a , 8b , and 8d -8i in the presence of CB [8] in water affords mostly the cis HH photodimers, and, also paralleling the cavity size effects of CDs, smaller CB [7] exclusively leads to the isomerization of the exocyclic double bond. 21 When protonated, azastilbenes are particularly prone to form inclusion compounds with CB [8].…”

“…Irradiation of cinnamates 8a , 8b , and 8d -8i in the presence of CB [8] in water affords mostly the cis HH photodimers, and, also paralleling the cavity size effects of CDs, smaller CB [7] exclusively leads to the isomerization of the exocyclic double bond. 21 When protonated, azastilbenes are particularly prone to form inclusion compounds with CB [8]. Interestingly, irradiation of aqueous solutions of the inclusion complexes selectively leads to the formation of the syn photodimers in the case of symmetrical 1,2 -dipyridiniumethylenes, whereas unsymmetrical analogs show preference for the anti photodimers ( Fig.…”

“…2.8 ). 26 Protonated stilbazoles (styrylpyridinium salts) also form inclusion compounds in CB [8], which behave similarly to the aforementioned unsymmetrical 1,2 -dipy ridiniumethylenes. 19,27 Anachenko et al 28 and Kaliappan et al 29 investigated the effect of calixarene hosts on the photochemistry of stilbenes and stilbazoles, respectively.…”