A Remarkable HBF₄-SiO₂-Catalyzed Synthesis of Acylals from Aldehydes under Solvent-Free Conditions

Abstract

HBF 4 -SiO 2 has been found to be an outstanding catalyst for the protection of carbonyl compounds as acylals under entirely solvent-free conditions. Some of the major advantages of this procedure are high yields, ease of operation, high chemoselectivity, high atom efficiency, and compatibility with other protecting groups.

HBF4‐Catalysed Nucleophilic Substitutions of Propargylic Alcohols

“…HBF 4 is a common acid in academic and industrial laboratories that has found diverse applications in synthesis, either as a reagent (nucleophilic fluorination,9 synthesis of vinylidene–metal complexes10), or catalyst (amidation of olefins,11 Biginelli reaction,12 acylation of aldehydes13). In particular, the Friedel–Crafts alkylation of benzylic alcohols in the presence of an excess of HBF 4 · OEt 2 solution at –78 °C has been reported 14.…”

Designs and Strategies for the Halo‐Functionalization of Diazo Compounds

“…HBF 4 is a benign fluoride source known as a versatile acid owing to its diverse applications in both industrial and academic synthesis . HBF 4 can be used as a catalyst for various reactions, including the acylation of aldehydes, Friedel–Crafts alkylation of 1‐aryl‐1‐alkanols, amidation of olefins, and the Bignelli reaction, and as a reagent in vinylidene metal complex synthesis and nucleophilic fluorination. Despite the notorious inertness and stability of tetrafluoroborates, HBF 4 is interestingly an effective alternative for fluorination …”

Silica-supported fluoroboric acid (HBF4–SiO2) catalyzed highly productive synthesis of thiomorpholides as activators of l-asparaginase as well as the antioxidant agent

“…13,14 In recent years, the use of catalysts immobilized on solid supports has received considerable attention. [15][16][17][18][19] Such catalysts not only simplify the purification process but also help in preventing the release of reaction residues into the environment. Thus, the solvent-less condition along with supported catalyst provides a protocol for achieving environment friendly organic synthesis.…”