Cascade radical reactions via carbon-carbon/heteroatom bond-forming process

Abstract

This article highlights our recent efforts toward developing the cascade reactions constructing the carbon-carbon and carbonheteroatom bond based on radical chemistry. The diethylzinc-promoted reaction of dehydroamino acid derivatives with acid anhydride or π-allyl palladium complex gave α,α-disubstituted amino acids via the radical and anionic carbon-carbon bond-forming process. This reaction was successfully expanded into the reductive transformation of N-phthaloyl dehydroalanine using Bu 3 SnH and Pd(PPh 3) 4. The chiral Lewis acid-mediated cascade radical addition-cyclization-trapping reaction proceeded smoothly with good enantioselectivities by using hydroxamate ester functionality as a chiral Lewis acid-coordinating tether between two radical acceptors. This method was applied into cascade reaction involving the unfavorable polarity-mismatched addition of electrophilic perfluoroalkyl radicals to electron-deficient acceptors. Additionally, cascade sequence terminated by radical-radical coupling was also reported.

Aqueous-Medium Carbon–Carbon Bond-Forming Radical Reactions Catalyzed by Excited Rhodamine B as a Metal-Free Organic Dye under Visible Light Irradiation

“…Therefore, the employment of uncharged radical species facilitates the construction of carbon–carbon bonds in aqueous media. , Recently, we studied the viability of ruthenium photocatalyst, Ru­(bpy) 3 Cl 2 ·6H 2 O, in the aqueous-medium perfluoroalkyl radical reactions . As a part of our studies on the radical reactions, we started to study the rhodamine B-catalyzed radical reactions in aqueous media. At first, we studied the reaction of alkenes 1 , 3 , and 5 with i -C 3 F 7 I in the presence of rhodamine B (5 mol %) under white light-emitting diode (LED) light irradiation.…”

Efficient bulk scale synthesis of popular pesticide synthon: tetrachlorothiophene

“…The interaction of heteroatoms with silica surface during heterocyclic reactions is reported and the acidic surface tends to support heterocyclic formations [54][55][56][57][58]. There are numerous acidic catalysts [59,60], especially Lewis acids [61,62] which are reported to aid in reaction cyclization by stabilizing the heteroatom. The Fe 3 O 4 @SiO 2 nanoparticles may primarily have reaction catalysis due to their size and increase in surface area, but the role of acidic surface-hetero atom interaction may also have a role.…”