Application of mixed phosphorus/sulfur ligands based on terpenoids in Pd-catalyzed asymmetric allylic substitution and Rh-catalyzed hydrogenation.

A small library of easily prepared diamidophosphite-sulfides based on 1,3-thioether alcohols, primarily of terpenoid nature, was developed. Upon complexation with Pd(II) ions, these hemilabile ligands showed the ability to form both P,S-chelates and complexes with two ligands P-monodentately bonded to the metal. The structures of the ligands and their complexes were determined by 2D NMR spectroscopy and X-ray diffraction. The use of these stereoselectors provided up to 95% ee in the classic Pd-catalyzed asymmetric allylic substitution reactions of (E)-1,3-diphenylallyl acetate with C- and N-nucleophiles and up to 80% ee in the Pd-mediated allylic alkylation of cinnamyl acetate with ß-ketoesters. In addition, ee values of up to 90% with quantitative conversion were achieved in the Rh-catalyzed asymmetric hydrogenation of methyl esters of unsaturated acids. The effects of the structural parameters, reaction conditions and ligand-to-metal ratio on the catalytic results are discussed.

Meso-Formyl, Vinyl, and Ethynyl Porphyrins-Multipotent Synthons for Obtaining a Diverse Array of Functional Derivatives.

This review presents a strategy for obtaining various functional derivatives of tetrapyrrole compounds based on transformations of unsaturated carbon-oxygen and carbon-carbon bonds of the substituents at the meso position (meso-formyl, vinyl, and ethynyl porphyrins). First, synthetic approaches to the preparation of these precursors are described. Then diverse pathways for the transformations of the multipotent synthons are discussed, revealing a variety of products of such reactions. The structures, electronic, and optical properties of the compounds obtained by the methods under consideration are analyzed. In addition, there is an overview of the applications of the products obtained. Biomedical use of the compounds is among the most important. Finally, the advantages of using the reviewed synthetic strategy to obtain dyes with targeted properties are highlighted.

Carbene functionalization of porphyrinoids through tosylhydrazones.

Here, we investigated methods for carbene functionalization of porphyrinoids through metal catalyst-free thermal decomposition of their tosylhydrazones. For the first time, tetrapyrrolyl substituted carbenes were obtained via thermolysis of tosylhydrazones of the corresponding tetrapyrrolyl aldehydes and ketones in the presence of a base. The carbenes formed reacted thermally with substrates without a metal catalyst or light irradiation. Carbenes at the ß-pyrrolic position of porphyrinoids reacted with styrene leading to cyclopropane derivatives of tetrapyrroles. Carbenes also reacted with 1,4-dioxane with their insertion into the C-H bond yielding a tetrapyrrole 1,4-dioxane conjugate. Thermolysis of tosylhydrazones of meso-formyl-ß-octaalkylporphyrinoids led exclusively to the corresponding cyclopentane fused porphyrinoids via intramolecular carbene C-H insertion. A plausible reaction mechanism was discussed based on DFT calculations of the intermediates. The tetrapyrrolyl carbenes were found to be considerably more stable than other carbenes. The products of the functionalization of porphyrinoids via hydrazone formation and subsequent carbene reactions exhibited modified optical spectra. The method for carbene functionalization of porphyrinoids through thermal decomposition of their tosylhydrazones created a new synthetic pathway for tailoring the perimeter of tetrapyrrolic macrocycles. Moreover, this method allows the obtainment of dyes with controllable spectral optical properties. In particular, new tetrapyrrole derivatives possessing phytoporphyrin carbon skeletons which have not been accessible were obtained using a convenient straightforward procedure.