Abstract
This account describes the development of organosulfonyloxy-substituted iodine(III)
and iodine(V) benziodoxole derived reagents, which are thermally stable compounds
with useful reactivity patterns. Iodine(III) benziodoxoles and pseudobenziodoxoles
are powerful electrophiles and mild oxidants toward various unsaturated compounds.
In particular, pseudocyclic benziodoxole-derived triflate (IBA-OTf) is an efficient
reagent for oxidative heteroannulation reactions. Aldoximes react with nitriles in
the presence of IBA-OTf at room temperature to give 1,2,4-oxadiazoles in high yields.
Moreover, IBA-triflate is used as a catalyst in oxidative heteroannulations with m-chloroperoxybenzoic acid as the terminal oxidant. The iodine(V) benziodoxole derived
tosylates, DMP-tosylate and IBX-tosylate, are superior oxidants for the oxidation
of structurally diverse, synthetically useful alcohols, utilized as key precursors
in the total syntheses of polyketide antibiotics and terpenes. And finally, the most
powerful hypervalent iodine(V) oxidant, 2-iodoxybenzoic acid ditriflate (IBX·2HOTf),
is prepared by treatment of IBX with trifluoromethanesulfonic acid. According to the
X-ray data, the I–OTf bonds in IBX-ditriflate have ionic character, leading to the
high reactivity of this reagent in various oxidations. In particular, IBX-ditriflate
can oxidize polyfluorinated primary alcohols, which are generally extremely resistant
to oxidation.
1 Introduction
2 Iodine(III) Benziodoxole Based Organosulfonates
3 Pseudocyclic Iodine(III) Benziodoxole Triflate (IBA-triflate)
4 Pseudocyclic Iodine(III) Benziodoxole Tosylates
5 Iodine(V) Benziodoxole Derived Tosylates
6 Iodine(V) Benziodoxole Derived Triflate (IBX-ditriflate)
7 Conclusions
Key words
hypervalent iodine - iodine - iodonium - 2-iodosylbenzoic acid (IBA) - 2-iodoxybenzoic
acid (IBX) - oxidation