Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

Abstract

SummaryBisureido- and a bisthioureido-substituted dibenzobarrelene derivative were synthesized and the photoreactivity of two representative examples were studied. Direct irradiation of the ureido-substituted derivative induces a di-π-methane rearrangement to the corresponding dibenzosemibullvalene derivative, whereas the thioureido-substituted derivative is almost photoinert. Complexes of the latter derivative with chloride, carboxylates, or sulfonate anions, however, are efficiently transformed to the dibenzosemibullvalene product upon irradiation, presumably by suppressing the self-quenching of the thiourea units in the complex. The association of the ureido-substituted dibenzobarrelene derivative with (S)-mandelate and irradiation of this complex led to the formation of the dibenzosemibullvalene with moderate stereoselectivity (68:32 er). In contrast, the thioureido derivative showed no such effect upon complexation of chiral anions.

5.06 Di-π-methane, Oxa-di-π-methane, and Aza-di-π-methane Photoisomerization

“…The high tolerance of functional groups in these reactions was also observed in the transformations of corresponding urea and thiourea derivatives 84. 53 Crown ether derivatives (85) have also been obtained. 54 A lot of dibenzobarrelene derivatives have been transformed in the solid phase.…”

“…Thus, the irradiation of the quaternary ammonium derivative 82 in acetone efficiently yielded the isomerization product 83 (Scheme 16). 52 Compound 83 was used as phase transfer catalyst in alkylation reactions. In particular in the alkylation of b-ketoesters, this compound was more efficient than the classical catalyst TBAC (tetrabutylammonium chloride).…”

Applications of Supramolecular Anion Recognition

“…A different approach toward the use of carboxylates is found in the work of Ihmels and co-workers . The hydrogen-bonding receptors are subjected to an asymmetric photoreaction themselves.…”

Bis‐thiourea Derivatives and Their Utility in Synthesis of Mono‐heterocyclic, Bis‐heterocyclic, and Fused Heterocyclic Systems

“…The dibenzobarrelene‐based bis‐thiourea derivative 84 was synthesized by reaction of the bis(diaminomethyl)dibenzobarrelene derivative 83 with the isothiocyanate 4 (Scheme ) .…”