HOF·CH₃CN: Probably the Best Oxygen Transfer Agent Organic Chemistry Has To Offer

Abstract

The complex HOF·CH3CN is readily obtained by bubbling dilute fluorine into aqueous acetonitrile solution. It does not have to be purified or isolated, and its solution can react as is, after the concentration has been establish by any iodometric method. It is the only reagent possessing a distinctive positive oxygen species. This enables electrophilic oxygen transfer with results no other reagent can match. HOF·CH3CN demonstrates its ability in epoxidations that either could not be performed before or could only obtained 5 orders of magnitude slower. This complex is also an excellent tool for oxygenation of compounds at the α position of a carbonyl, including the synthesis of some hard-to-come-by indanediones, which are important for fingerprint visualization on paper. HOF·CH3CN proves itself as a very efficient reagent for oxygenating tertiary nitrogen atoms both in aliphatic (including azides) and in aromatic amines, which could not be accomplished despite many attempts in the last 50 years. Oxygenation of two tertiary nitrogen atoms in the same molecule also becomes feasible as demonstrated for various phenanthrolines, bipyridines, diazafluorenones, and quinoxalines. It was also used to oxygenate primary amines, and because of the exceptionally mild conditions, it could transform vicinal aliphatic diamines to vicinal dinitro derivatives as well as amino acids to the corresponding nitro ones, practically unknown transformations before. Its ability to react with azines and hydrazones and convert them to the original carbonyls helped to establish these groups as good protecting tools for a variety of carbonyls. HOF·CH3CN excels in oxygenation of various sulfur and selenium compounds that could not be oxygenated in the past. The selectivity of the oxidation is quite good, and if there are alcohols, double bonds, and sulfides in the same molecule, usually the sulfur atom will be attacked first. Of special interest is the reaction with oligothiophenes resulting at will in either [all]-S,S-dioxooligothiophenes or in partially oxygenated ones. Some of these last derivatives have the narrowest HOMO-LUMO gap of all oligothiophenes tested, a very desirable feature. This reagent can also oxidize thiols or disulfides to either sulfonic or sulfinic acids at will, all in seconds and in very high yields. Since the oxygen atom of HOF·CH3CN originates in water, it is very easy and relatively inexpensive to introduce the heavy oxygen isotope in many sites of a variety of molecules, some of them quite important. The (18)O tirapazamine and any desirable alcohol, R(Ar)(18)OH, are two examples.

Tuning the polarity of charge carriers using electron deficient thiophenes

“…We chose the T P unit because it is a ubiquitous electron poor building block in high performance donor–acceptor type materials for organic electronics. 30–37 Moreover, we also highlight in Scheme 1 that the use of the electrophilic oxygen in Rozen's reagent (HOF·CH 3 CN) 38–40 enabled the synthesis of an oxidized thienopyrrolodione (O P ). T P is an extremely challenging unit to oxidize into O P because the electron-withdrawing substituents at the 3,4-position make the sulfur weakly nucleophilic (Scheme 1).…”

Molecular length dictates the nature of charge carriers in single-molecule junctions of oxidized oligothiophenes

“…The general procedure to synthesize these molecules is as follows (see the Supplementary Information for details). First, a dibromo-terminated oligothiophene was treated with Rozen's reagent40 . Rozen's reagent is a stabilized form of hypofluorous acid that can be used to oxidize the thiophene units.…”

[All]‐S,S‐dioxide Oligo‐Thienylenevinylenes: Synthesis and Structural/Electronic Shapes from Their Molecular Force Fields

“…Among the offspring of F 2 , one can mention acetyl hypofluorite (AcOF), methyl hypofluorite (MeOF), bromine trifluoride (BrF 3 ) and, especially, the acetonitrile complex of the hypofluorous acid (HOF ⋅ CH 3 CN), readily made by passing dilute F 2 through aqueous acetonitrile . Currently, the last reagent is considered to be one of the best oxygen transfer agent chemistry has to offer . Among other unprecedented transformations the electrophilic oxygen of the reagent has been successfully used in preparation of several [all]‐ S , S ‐dioxooligothiophenes, including certain relevant nanoparticles .…”

“…[29] Currently, the last reagent is considered to be one of the best oxygen transfer agent chemistry has to offer. [30][31][32] Among other unprecedented transformationst he electrophilic oxygen of the reagent has been successfully used in preparation of several[ all]-S,S-dioxooligothiophenes, [33] includingc ertainr elevant nanoparticles. [34] Even more,o ne of the advantages of this reagent is that its source of electrophilic oxygen is water.…”