A Phosphonium Ylide as an Ionic Nucleophilic Catalyst for Primary Hydroxyl Group Selective Acylation of Diols

Abstract

Carbonyl-stabilized phosphonium ylides exhibit great utility in modern organic synthesis, and they are known as an ambident nucleophile at the carbonyl oxygen atom and at the α-carbon atom. However, they have found limited use as catalysts. We focused on the inherent nucleophilicity of the oxygen atom to develop an ionic nucleophilic catalysis, and the phosphonium ylide-catalyzed primary alcohol selective acylation of mixed diols with acid anhydrides has been demonstrated. Mechanistic studies revealed the behavior of a catalyst, which would contribute to the field of ylide chemistry.

DBN‐Catalyzed Regioselective Acylation of Carbohydrates and Diols in Ethyl Acetate

“…In 2013, Tan and co‐workers developed N ‐methylimidazole‐derived catalysts for the selective functionalization of carbohydrates, which is a great progress for represents a great advance in the recognition regioselective derivatization of complex polyhydroxyl species . Recently, a phosphonium ylide was developed as a catalyst for the highly regioselective acetylation of primary hydroxyl groups, but its substrate scope is restricted . Some peptides can also catalyze the regioselective acylation of carbohydrates, and they often provide good selectivities with a particular kind of substrate …”

Visible‐Light‐Induced Pyridylation of Remote C(sp3)−H Bonds by Radical Translocation of N‐Alkoxypyridinium Salts

“…[4,5] Given the ubiquity of hydroxy groups in organic molecules,t he development of mild catalytic strategies that enable the direct conversion of OÀHbonds into Ocentered radicals is an attractive approach for remote CÀH activation with broad utility.F rom as ynthetic perspective, hydroxy groups are among the most versatile functional groups for subsequent transformations,a nd the scope of this class of compound can be leveraged to provide access to aw ide range of synthetic targets. [6] Recently,t he groups of Chen [7] and Meggers [8] independently described Ir-based photocatalyzed generation of O-centered radicals from alkoxy radical precursors,N -alkoxyphthalimides,t oa chieve remote CÀHf unctionalizations by exploiting a1 ,5-HAT event. In these cases,t he Hantzsch ester is required as the reductant to promote the catalytic reaction, and phthalimide is generated as abyproduct.…”

Visible‐Light‐Induced Pyridylation of Remote C(sp3)−H Bonds by Radical Translocation of N‐Alkoxypyridinium Salts

“…[3] Classically,t he functionalization of nonactivated remote CÀHb onds can be achieved by free-radical transposition of O-and N-centered radicals,i nw hich the site selectivity is controlled by an intramolecular 1,5-hydrogen-atom transfer (1,5-HAT) event. [6] Recently,t he groups of Chen [7] and Meggers [8] independently described Ir-based photocatalyzed generation of O-centered radicals from alkoxy radical precursors,N -alkoxyphthalimides,t oa chieve remote CÀHf unctionalizations by exploiting a1 ,5-HAT event. [6] Recently,t he groups of Chen [7] and Meggers [8] independently described Ir-based photocatalyzed generation of O-centered radicals from alkoxy radical precursors,N -alkoxyphthalimides,t oa chieve remote CÀHf unctionalizations by exploiting a1 ,5-HAT event.…”