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Biomimetic oxidative dimerization of tryptophan derivatives in aqueous media with oxygen as a bulk oxidant catalyzed by an iron octacarboxy phthalocyanine complex was established. The discovery of the extremely active iron catalyst enables aerobic enzyme-mimetic oxidation to be performed in a flask. This method was applicable to the oxidative dimerization of a wide range of tryptophan derivatives, including various dipeptides and oligopeptides, with remarkable functional-group tolerance without the protection of the amino acid residues. Furthermore, oxidative dimerization of tryptophan derivatives bearing dioxopiperazine units enabled the convergent total synthesis of five natural pyrroloindole compounds and unnatural congeners. The established chemical method provides facile access to a broad range of dimerized peptides with a unique scaffold to link two turn structures, which will serve as a powerful tool to create new small- and medium-sized-molecules as drug candidates., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

We have established a highly convergent 10-step route for the total synthesis of (-)-deoxoapodine, which is a hexacyclic aspidosperma alkaloid. The quaternary C5 center of the characteristic tetrahydrofuran ring was constructed by a chiral-phosphoric-acid-catalyzed enantioselective bromocycloetherification in a 5-endo fashion and subsequent allylation by using the Keck protocol. Construction of the aspidosperma skeleton features the formation of a nine-membered lactam by a catalytic C-H palladation/alkylation cascade at the indole 2-position and an iron-catalyzed oxidative transannular reaction at a late-stage of the synthesis., (© 2020 Wiley-VCH GmbH.)

A cationic fluorescent nanogel thermometer based on thermo-responsive N-isopropylacrylamide and environment-sensitive benzothiadiazole was developed with a new azo compound bearing imidazolium rings as the first cationic radical initiator. This cationic fluorescent nanogel thermometer showed an excellent ability to enter live mammalian cells in a short incubation period (10 min), a high sensitivity to temperature variations in live cells (temperature resolution of 0.02-0.84 °C in the range 20-40 °C), and remarkable non-cytotoxicity, which permitted ordinary cell proliferation and even differentiation of primary cultured cells., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein we report a total synthesis of the indolohydroazocine natural product actinophyllic acid. The target molecule was retrosynthetically deconvoluted to render a greatly simplified and symmetrical [4.4.1] bicyclic trienone, the desymmetrization of which was carefully examined under a variety of conditions, including oxidative, reductive, and transition-metal-catalyzed transformations. Ultimately, the successful synthetic strategy featured chemoselective catalytic dihydroxylation, desymmetrizing nitrile oxide dipolar cycloaddition, and palladium-catalyzed aminoarylation to sequentially modify the three olefins within the trienone, followed by a late-stage reductive cascade indolization and alkylation to complete the target molecule., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Stereoselective total syntheses of (-)-histrionicotoxin and (-)-histrionicotoxin 235A are described. The 1-azaspiro[5.5]undecane skeleton was constructed diastereoselectively by a radical translocation-cyclization reaction involving a chiral cyclic acetal; the use of tris(trimethylsilyl)silane was crucial for the high diastereoselectivity. The cyclization product was converted into (-)-histrionicotoxin 235A through a one-pot partial-reduction-allylation reaction of a derivative containing an unprotected lactam. Finally, two terminal alkenes were transformed into enynes with the 1,3-amino alcohol protected as an oxathiazolidine oxide to complete the total synthesis of (-)-histrionicotoxin., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A bioinspired convergent total synthesis of (+)-haplophytine, a dimeric indole alkaloid with diazabicyclo[3.3.1]nonane and hexacyclic aspidosperma segments, is described. This synthesis involves the direct coupling of the two segments in a AgNTf 2 -mediated Friedel-Crafts reaction and construction of the diazabicyclo[3.3.1]nonane skeleton through late-stage chemoselective aerobic oxidation of the 1,2-diaminoethene moiety and a sequential semipinacol-type rearrangement., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first total synthesis of an epidithiodiketopiperazine alkaloid, (+)-MPC1001B, was accomplished. This synthesis features a tetra-n-butylammonium fluoride mediated intramolecular aldol reaction for forming the 15-membered macrolactone ring, and the construction of an epidithiodiketopiperazine substructure through a stepwise sulfenylation reaction involving a novel trityl trisulfide (TrSSS)-group transfer., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The enantiocontrolled total synthesis of (-)-haouamine B pentaacetate was accomplished via an optically active indane-fused β-lactam, which was prepared by a newly developed Friedel-Crafts reaction. Subsequent cleavage of the β-lactam and an intramolecular McMurry coupling reaction provided the core indane-fused tetrahydropyridine, which led to the elucidation of the structure, as proposed by Trauner and Zubía., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The key step in this total synthesis of (-)-acetylaranotin is the efficient formation of the characteristic dihydrooxepine ring from cyclohexenone through an unusual vinylogous Rubottom oxidation and a regioselective Baeyer-Villiger oxidation. (-)-Acetylaranotin is obtained in 22 steps from commercially available L-Cbz-tyrosine (Cbz=benzyloxycarbonyl)., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)