Pseudocyclic Arylbenziodoxaboroles: Efficient Benzyne Precursors Triggered by Water at Room Temperature

Abstract

New organohypervalent iodine compounds, arylbenziodoxaborole triflates, were prepared from 1-acetoxybenziodoxaboroles and arenes by treatment with trifluoromethanesulfonic acid under mild conditions. Single crystal X-ray crystallography of these compounds revealed a pseudocyclic structure with a short intramolecular interaction of 2.698 to 2.717 Å between oxygen and iodine in the benziodoxaborole ring. These new pseudocyclic aryliodonium salts readily generate aryne intermediates upon treatment with water at room temperature. The generated aryne intermediates react with various substrates to give the corresponding aryne adducts in moderate to good yields. Furthermore, the new benzyne precursors can also work as arylating reagents towards aromatic rings. The aryne intermediates generated from arylbenziodoxaborole triflates selectively react with tert-butyl phenol forming products of ortho arylation in moderate yields.

Iodonium Salts as Benzyne Precursors

“…Pseudocyclic arylbenziodoxaborole triflates 90 represent unique benzyne precursors that can be activated by water at room temperature . Compounds 90 are prepared from 1‐acetoxybenziodoxaboroles 88 and arenes 89 by treatment with trifluoromethanesulfonic acid under mild conditions (Scheme ).…”

“…The generated aryne intermediates can be trapped with various substrates to give the corresponding aryne adducts in moderate to good yields. In a specific example, the reaction of reagent 91 with benzyl azide 92 in the presence of water affords triazole 93 in 78 % yield (Scheme ) …”

“…Pseudocyclic arylbenziodoxaborole triflates 90 represent unique benzyne precursors that can be activated by water at room temperature. [43] Compounds 90 are prepared from 1-acetoxybenziodoxaboroles 88 and arenes 89 by treatment with trifluoromethanesulfonica cid under mild conditions (Scheme30). Single crystal X-ray crystallography of these compounds revealed ap seudocyclic structure with as hort intramolecular interaction about 2.7 between oxygen and iodine in the benziodoxaborole ring.…”

“…Diaryliodonium salts with a silyl substituent in ortho position such as phenyl[2‐(trimethylsilyl)phenyl]iodonium triflate (Kitamura's reagent) 1 c can produce benzyne species via desilylation by fluoride source . Very recently, our group reported the preparation and structural investigation of novel benzyne precursors, pseudocyclic arylbenziodoxaborole triflates 1 d , which can readily generate benzyne species via deboronation reaction triggered by water …”

“…[38][39][40][41][42] Very recently,o ur group reported the preparation and structurali nvestigation of novel benzyne precursors, pseudocyclic arylbenziodoxaborole triflates 1d,w hich can readily generateb enzyne species via deboronation reaction triggered by water. [43] In the presentm inireview,w ed iscuss the preparation and reactions of diaryliodonium derivatives, which can be used for the generation of benzyne intermediates under mild conditions. Recent developments in their synthetic application are also summarized.…”