Recent progress in alkynylation with hypervalent iodine reagents

Abstract

Although alkynes are one of the smallest functional groups, they are among the most versatile building blocks for organic chemistry. In this feature article, the progress in alkynylation with hypervalent iodine reagents since 2018 will be presented.

Carboiodanation of Arynes: Organoiodine(III) Compounds as Nucleophilic Organometalloids

“…As a consequence, organohalogen and organometallic compounds manifest themselves as quintessential carbon electrophiles and nucleophiles, respectively (Figure A, left). Notably, organoiodine­(III) compounds, also known as organo-λ 3 -iodanes, represent a distinctive category of carbon electrophiles that consist of a transferable carbon ligand (R), an electronegative group or counteranion (Y), and a static aryl substituent (Ar) arranged in a T-shaped configuration . These compounds conventionally engage with a nucleophile (Nu – ), either autonomously or with the assistance of a catalyst, to form an R–Nu bond while concurrently expelling iodoarene (Ar–I) and Y anion as nucleofuges (Figure A, right).…”

Distal iodine migration of arylalkynes via cyclic monoaryliodonium salts

“…Linear vinylaryliodoniums and alkynylaryliodoniums are very popular vinyl and alkynyl functional groups that transport reagents in a variety of cross-coupling reactions. 8 Inspired by the preparation of these iodoniums, we hold an idea that iodoethynylarenes are promising precursors for CMAIs, which is illustrated in Scheme 2: m CPBA (3-chloroperoxybenzoic acid) oxidation of 1-(iodoethynyl)-4-methylbenzene 1a generated intermediate 1a-i , which could be protonated and nucleophilically attacked by TfOH, forming 1a-ii and 1a-iii . Protonation of 1a-iv led to 1a-v , which could be intramolecularly dehydrated to give the anticipated CMAI 2a .…”

Recent Progress in Synthetic Applications of Cyclic Hypervalent Iodine(III) Reagents

“…[4] The applications of aryl-, alkynyl-, and alkenylbenziodoxoles as efficient reagents for direct arylation, alkynylation, and alkenylation of various organic substrates were comprehensively reviewed in 2023. [8][9] The chemistry of benziodoxole sulfonates as powerful oxidants and electrophilic reagents was summarized in the 2020 review. [10] The present review covers the most recent works on synthetic applications of other classes of benziodoxolebased reagents published mainly in the last 5 years.…”

“…All other important reagents shown in Figure 1 are derived from the readily available heterocyclic system of benziodoxole [4] . The applications of aryl‐, alkynyl‐, and alkenylbenziodoxoles as efficient reagents for direct arylation, alkynylation, and alkenylation of various organic substrates were comprehensively reviewed in 2023 [8–9] . The chemistry of benziodoxole sulfonates as powerful oxidants and electrophilic reagents was summarized in the 2020 review [10] .…”