Synthesis of tryptophan-containing 2,5-diketopiperazines via sequential C–H activation: total syntheses of tryprostatin A, maremycins A and B

Abstract

Indole 2,5-diketopiperazines (DKPs) are an important type of metabolic cyclic dipeptides containing a tryptophan (Trp) unit possessing a range of interesting biological activities. The intriguing structural features and divergent activities...

An indole diketopiperazine alkaloid and a bisabolane sesquiterpenoid with unprecedented skeletons from Aspergillus fumigatus

“…17 Due to their fascinating structures and biological activities, indole diketopiperazines and sesquiterpenoids have attracted increasing attention from the biosynthetic, organic synthetic, and phytochemical communities. 6,7,[21][22][23] The fungus Aspergillus fumigatus is a rich source of indole diketopiperazines, notably neoechinulin A (R1), which exhibited a potent inhibitory effect against SARS-CoV-2 M pro with an IC 50 value of 0.47 μM, which is comparable to the reference standard GC376. 24 In addition to indole diketopiperazine, spirolactam alkaloids [pseurotin A (R6) had inhibitory effect on glioma cells with an IC 50 value of 0.51 μM], fumiquinazolines [fumiquinazoline A (R7) possessed antifeedant activity with antifeedant index of 45.0%], tryptoquivalines [tryptoquivaline J (R8) inhibited the proliferation of breast cancer cells], terpenoids [ pyripyropene A (R11) displayed inhibition of cholesterol acyltransferase with an IC 50 value of 0.058 μM], and polyketones [sulfurasperine D (R14) exhibited antioxidant activity with an IC 50 value of 1.65 μM] are also their metabolites, as shown in Fig.…”

“…17 Due to their fascinating structures and biological activities, indole diketopiperazines and sesquiterpenoids have attracted increasing attention from the biosynthetic, organic synthetic, and phytochemical communities. 6,7,21–23…”

Concise Synthesis of 2,5-Diketopiperazines via Catalytic Hydroxy-Directed Peptide Bond Formations

“…Although diverse synthetic methodologies have been reported to construct 2,5-diketopiperazines, − including tandem intramolecular N -alkylation of Ugi four-component reaction products, intramolecular C-acylation of peptide enolates, and intramolecular Tsuji–Trost allylation, one of the direct and versatile approaches to synthesize DKPs is the condensation between two amino acids followed by intramolecular cyclization of dipeptide sequences . A significant advantage of this process is the ability to synthesize diversity-oriented DKPs using readily available amino acid components.…”

Temperature-induced formation of Pd nanoparticles in heterogeneous nanobiohybrids: application in C–H activation catalysis

“…[32][33][34] The functionalization of tryptophan in C-2 by C-H activation was performed by Pd-catalysis for drugs total synthesis. 35 Different organometallics, palladium salts, or immobilized systems have been applied in this reaction; however, in all cases, longer time reaction or high T has been necessary (Scheme S1 †). 26,[36][37][38] Herein, we successfully demonstrated our Pd strategy for simple, efficient, and rapid C-H activation (Scheme 1).…”