No abstract

Vinyl azides are very reactive species and as such are useful building blocks, in particular, in the synthesis of N-heterocycles. They can also serve as precursors of ketones. These form in reactions of vinyl azides with nucleophiles or radicals. We have found, however, that under light irradiation vitamin B 12 catalyzes the reaction of vinyl azides with electrophiles to afford unsymmetrical carbonyl compounds in decent yields. Mechanistic studies revealed that alkyl radicals are key intermediates in this transformation.

6,7‐Bis[3‐(Nϵ‐tert‐butyloxycarbonyllysine methyl ester)]‐1,3,5,8‐tetramethyl‐2,4‐divinylporphyrin (3) was synthesized and successfully immobilized in a silica matrix by a sol–gel method. Protoporphyrin (PP)‐derived amide 3 showed much higher photostability than its parent PP‐IX. Its UV/Vis absorption, excitation, and fluorescence spectra as well as its ability to generate 1O2 were measured both in solution and in the matrix. Subsequently, free and immobilized porphyrins 3 were used as sensitizers in the photooxidation of α‐pinene, and their photocatalytic properties were compared.