Azobenzene/Tetraethyl Ammonium Photochromic Potassium Channel Blockers: Scope and Limitations for Design of Para-Substituted Derivatives with Specific Absorption Band Maxima and Thermal Isomerization Rate.

Azobenzene/tetraethyl ammonium photochromic ligands (ATPLs) are photoactive compounds with a large variety of photopharmacological applications such as nociception control or vision restoration. Absorption band maximum and lifetime of the less stable isomer are important characteristics that determine the applicability of ATPLs. Substituents allow to adjust these characteristics in a range limited by the azobenzene/tetraethyl ammonium scaffold.

Isoxazole Strategy for the Synthesis of α-Aminopyrrole Derivatives.

The synthesis of methyl 5-aminopyrrole-3-carboxylates from 4-methyleneisoxazol-5-ones via "cyanide Michael addition/methylation/reductive isoxazole-pyrrole transformation" is developed. The last step occurs in a domino mode involving Mo(CO)-mediated reductive isoxazole ring-opening, Mo(CO)-catalyzed --isomerization of the enamine intermediate followed by 1,5-- cyclization. 5-Amino-1-pyrrolo-3-carboxylates react with 1,3-diketones, affording pyrrolo[1,2-]pyrimidine-7-carboxylates, and are easily converted into 2-diazo-2-pyrrole-4-carboxylates.