Self-assembly of a (benzothiazolyl)ethenylbenzocrown ether into a sandwich complex and stereoselective [2+2] photocycloaddition

Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions

The [2 + 2] photocycloaddition is undisputedly the most important and most frequently used photochemical reaction. In this review, it is attempted to cover all recent aspects of [2 + 2] photocycloaddition chemistry with an emphasis on synthetically relevant, regio-, and stereoselective reactions. The review aims to comprehensively discuss relevant work, which was done in the field in the last 20 years (i.e., from 1995 to 2015). Organization of the data follows a subdivision according to mechanism and substrate classes. Cu(I) and PET (photoinduced electron transfer) catalysis are treated separately in sections 2 and 4 , whereas the vast majority of photocycloaddition reactions which occur by direct excitation or sensitization are divided within section 3 into individual subsections according to the photochemically excited olefin.

Influence of the anion nature on styryl dye crystal packing and feasibility of the direct and back [2 + 2] photocycloaddition reactions without single crystal degradation

By X-ray diffractometry, [2 + 2]-photocycloaddition reaction and its back reaction were investigated.

Regio- and stereospecific [2+2] photocyclodimerization of a crown-containing butadienyl dye via cation-induced self-assembly in solution

Self-assembled pseudocyclic structures consisting of two molecules of a crown-containing butadienyl dye and two Mg(2+) ions readily undergo regio- and stereospecific [2+2] photocycloaddition in MeCN to produce a single cyclobutane stereoisomer in almost quantitative yield.

Novel amidino-substituted benzimidazoles: Synthesis of compounds and inhibition of dipeptidyl peptidase III

Dipeptidyl peptidase III (DPP III), also known as enkephalinase B, is a zinc-hydrolase with an indicated role in the mammalian pain modulatory system. In order to find a potent antagonist of this enzyme, we synthesized and screened the effect of a small set of benzimidazole derivatives on its activity. To improve the inhibitory potential, a cyclobutane ring was introduced as rigid conformation support to the diamidino substituted dibenzimidazoles. Two such compounds (1' and 4') from the group of cyclobutane derivatives containing amidino-substituted benzimidazole moieties, obtained by photochemical cyclization in water and by respecting rules of the "green chemistry" approach, were found to be strong DPP III inhibitors, with IC(50) value below 5 microM. Compound 1' displayed time-dependent inhibition towards human DPP III, characterized by the second-order rate constant of 6924+/-549 M(-1)min(-1) (K(i)=0.20 microM). The peptide substrate valorphin protected the enzyme from inactivation by 1'.