Total Synthesis of (+)-Gliocladin C Based on One-Pot Construction of a 3a-(3-Indolyl)pyrroloindoline Skeleton by Sulfonium-Mediated Cross-Coupling of Tryptophan and Indole

Abstract

Total synthesis of (+)-gliocladin C has been achieved on the basis of one-pot construction of the 3a-(3-indolyl)pyrroloindoline core structure by the cross-coupling of a tryptophan derivative and an indole promoted by a sulfonium species generated from dialkylsulfoxide and triflic anhydride.

Enantioselective synthesis of mixed 3,3′-bisindoles via a phosphine-catalyzed umpolung γ-addition of 3′-indolyl-3-oxindoles to allenoates

“…Compound 7 then underwent a three-component reaction with benzoyl hydrazine and TMSCN to afford a-aminonitirile 8 in a highly diastereoselective manner. Finally, hydrolysis and reductive cyclization furnished compound 9, the core structure of Gliocladin C and its related nature product family [81][82][83][84][85][86][87] (Scheme 5).…”

Triflic Anhydride (Tf2O)-Activated Transformations of Amides, Sulfoxides and Phosphorus Oxides via Nucleophilic Trapping

“…With the versatile synthetic tool in hand, the Kawasaki group applied this transformation for a concise synthesis of natural products including (±)-folicanthine 58e, (±)calycanthidine 58f, (±)-chimonanthidine 58g, and (+)-gliocladin C 58h. 101 In 2017, this thionium reagent was also applied for the synthesis of C2functionalized indole cores commonly found in biologically active alkaloids and pharmaceuticals. 102 Scheme 58.…”

Alkylation Reactions with Alkylsulfonium Salts

“…33f Moreover, the total synthesis of (+)-gliocladin C was implemented on the basis of a 3a-(indol-3-yl)pyrroloindoline structure that was built by sulfonium-promoted cross-coupling of a tryptophan derivative with indole in the presence of dialkyl sulfoxide and Tf 2 O. 33g Likewise, the sulfonium-triggered direct C2-functionalization of indoles 141 with different kinds of nucleophiles 142 was explored (Scheme 17c ). 33h Reaction of 141 with the in situ formed sulfonium salt from DMSO/Tf 2 O generates iminium species 144 , which is attacked by 142 followed by elimination of dimethyl sulfide, to afford the corresponding C2-substituted indole derivatives 143 in good to high yields.…”