Synthesis of cis-β-Amidevinyl Benziodoxolones from the Ethynyl Benziodoxolone–Chloroform Complex and Sulfonamides

Abstract

The synthesis of cis-β-amidevinyl benziodoxolones from the ethynyl benziodoxolone–chloroform complex and sulfonamides is reported. Evidence indicates that highly reactive unsubstituted ethynyl benziodoxolone undergoes Michael addition of sulfonamides, including sterically demanding acyclic amino acid derivatives. The synthesis of selectively deuterated cis-β-amidevinyl benziodoxolones and investigation of ethynyl-λ3-iodane reactivity are also described.

Vinylbenziodoxol(on)es: Synthetic Methods and Applications

“…In 2019, Itoh, Tada and coworkers reported the synthesis of cisβ-amidevinyl benziodoxolones from an ethynyl-1,2-benziodoxol-3(1H)-one-chloroform complex (36d). [93] The reaction proceeded under mild conditions, in presence of a catalytic amount of base and sulfonamides derived from various amines, including amino acids, could be used as nucleophiles for the transformation. Hypervalent iodine reagents 45d-45f could be accessed in excellent yields.…”

“…[62] Copper-catalyzed reduction is another effective meth-od used by the groups of Yoshikai, Itoh and Tada, to reduce the benziodoxol(on)es moiety without affecting the olefin configuration. [93,94] Using a copper(I) reductant, iodine 57 and 58 were obtained in good yields at 50°C. Metal Catalyzed CÀ C Bond Formation.…”

“…During this work, one example of unsubstituted N‐VBX 45 could be obtained from trimethylsilyl‐EBX ( 36c ), with in situ desilylation ( Scheme 23). In 2019, Itoh , Tada and coworkers reported the synthesis of cis ‐β‐amidevinyl benziodoxolones from an ethynyl‐1,2‐benziodoxol‐3(1 H )‐one‐chloroform complex ( 36d ) [93] . The reaction proceeded under mild conditions, in presence of a catalytic amount of base and sulfonamides derived from various amines, including amino acids, could be used as nucleophiles for the transformation.…”

“… [90] Photoredox conditions were also used by our group to cleave the hypervalent bond of N‐VBX 45 , delivering the monovalent compound 56 [62] . Copper‐catalyzed reduction is another effective method used by the groups of Yoshikai , Itoh and Tada , to reduce the benziodoxol(on)es moiety without affecting the olefin configuration [93,94] . Using a copper(I) reductant, iodine 57 and 58 were obtained in good yields at 50 °C.…”

Synthesis of Phenol‐Derived cis‐Vinyl Ethers Using Ethynyl Benziodoxolone

“…They can be prepared from ethynyl benziodoxol(on)es (EBXs) or alkynes and iodosylbenzoic acid derivatives under mild reaction conditions (Scheme 1A). [19][20][21][22][23] Notably, VBXs can be further derivatized into various vinyl compounds. Recently, Miyake and co-workers reported the preparation of Z-β-phenoxyvinyl benziodoxolones using 1.5 equivalent of Cs 2 CO 3 under dark conditions to evaluate the mechanism of light-driven synthesis of Z-2iodovinyl aryl ethers from ethynyl benziodoxolones and phenols (Scheme 1B).…”