Study of the Reactivity of [Hydroxy(tosyloxy)iodo]benzene Toward Enol Esters to Access α-Tosyloxy Ketones

Abstract

The reactivity of enol esters toward [hydroxy(tosyloxy)iodo]benzene (HTIB) was assessed. These substrates were found to be rapidly converted in high yields to their corresponding α-tosyloxy ketones. This transformation demonstrates that these substrates can act as ketone surrogates. The scope of the method was investigated and aromatic, aliphatic, and cyclic enol esters were found to be suitable substrates for the reaction. The relative reactivity of a model substrate toward HTIB and m-CPBA was investigated, and it was found that the reaction could be performed under catalytic conditions.

Cyclization of Malonate Derivatives with Iodine(III) Reagents

“…The mild reaction conditions associated with the low toxicity and the environmentally friendly behaviour of these compounds render them attractive for organic synthesis Hypervalent iodine reagents are very selective oxidants and several derivatives have been reported as enantiomerically pure reagents . Due to their electrophilic nature and their excellent leaving‐group ability, they can react with a broad range of nucleophiles in reactions such as the oxidation of sulfides to sulfoxides, the dearomatization of phenols, the α‐arylation and the α‐oxygenation of carbonyl compounds but also in the functionalization of carbon–carbon double bonds through dioxygenation, diamination, oxyamination, iodoamination, oxytrifluoromethylation or aminofluorination . The facile generation of cationic intermediates by hypervalent iodine reagents allows either the direct reaction with a nucleophile or the formation of rearranged products with ring contraction, ring expansion or aryl migration .…”

Enol Ester Synthesis via Cobalt-Catalyzed Regio- and Stereoselective Addition of Carboxylic Acids to Alkynes

“…The enol ester 5ai could be transformed into triphenylethene ( 6 ) via a nickel-catalyzed cross-coupling reaction . Ketones 7 and 8 were obtained smoothly under hydrolysis and oxidation conditions, respectively …”

Stereoselective Ketone Rearrangements with Hypervalent Iodine Reagents

“…Under the reaction conditions employed, it is also plausible that the presence of triflic acid and trimethyl orthoformate will lead to the formation of the enol 15 a via ketal 14 . Although it is not identifiable in the NMR, it could react with the iodine(III) species in the presence of methanol to form intermediate 12 .…”