The hetero-Friedel-Crafts-Bradsher Cyclizations with Formation of Ring Carbon-Heteroatom (P, S) Bonds, Leading to Organic Functional Materials

Abstract

The interest in functional materials possessing improved properties led to development of new methods of their synthesis, which allowed to obtain new molecular arrangements with carbon and heteroatom motifs. Two of the classical reactions of versatile use are the Friedel-Crafts and the Bradsher reactions, which in the new heteroatomic versions allow to replace ring carbon atoms by heteroatoms. In the present work, we review methods of synthesis of C–S and C–P bonds utilizing thia- and phospha-Friedel-Crafts-Bradsher cyclizations. Single examples of C–As and lack of C–Se bond formation, involving two of the closest neighbors of P and S in the periodic table, have also been noted. Applications of the obtained π-conjugated molecules, mainly as semiconducting materials, flame retardants, and resins hardeners, designed on the basis of five- and six-membered cyclic molecules containing ring phosphorus and sulfur atoms, are also included. This comprehensive review covers literature up to August 2020.

Synthetic Strategies for Accessing Dibenzophosphole Scaffolds

“…An intramolecular PFC reaction was developed initially. 35 In 1961, Campbell et al synthesized dibenzophosphole oxides by the treatment of biarylphenylphosphinic acids with PCl5 (Scheme 23). 36…”

“…An intramolecular PFC reaction was developed initially. 35 In 1961, Campbell and Way synthesized dibenzophosphole oxides by the treatment of biphenyl-2-ylphenylphosphinic acids with PCl 5 (Scheme 23). 36 In 2000, López-Calahorra and co-workers reported a similar reaction of a biphenyl-2-ylmethylphosphinic acid (Scheme 24).…”