Browsing by Author "Heretsch, Philipp"

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    Synthesis and Biological Evaluation of QRSTUVWXYZA' Domains of Maitotoxin
    (American Chemical Society, 2014) Nicolaou, K.C.; Heretsch, Philipp; Nakamura, Tsuyoshi; Rudo, Anna; Murata, Michio; Konoki, Keiichi; BioScience Research Collaborative
    The synthesis of QRSTUVWXYZA′ domains 7, 8, and 9 of the highly potent marine neurotoxin maitotoxin (1), the largest secondary metabolite isolated to date, is described. The devised synthetic strategy entailed a cascade Takai–Utimoto ester olefination/ring closing metathesis to construct ring Y, a hydroxydithioketal cyclization/methylation sequence to cast ring X, a Horner–Wadsworth–Emmons coupling of WXYZA′ ketophosphonate 11 with QRSTU aldehyde 12 to form enone 10, and a reductive hydroxyketone ring closure to forge ring V. 2D NMR spectroscopic analysis and comparison of 13C chemical shifts with those of the corresponding carbons of maitotoxin revealed close similarities supporting the originally assigned structure of this region of the natural product. Biological evaluations of various synthesized domains of maitotoxin in this and previous studies from these laboratories led to fragment structure–activity relationships regarding their ability to inhibit maitotoxin-elicited Ca2+ influx in rat C6 glioma cells.
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    Total Synthesis of Δ12-Prostaglandin J3, a Highly Potent and Selective Antileukemic Agent
    (Wiley, 2014) Nicolaou, K.C.; Heretsch, Philipp; ElMarrouni, Abdelatif; Hale, Christopher R.H.; Pulukuri, Kiran K.; Kudva, Avinash K.; Narayan, Vivek; Prabhu, K. Sandeep; BioScience Research Collaborative
    A catalytic asymmetric total synthesis of the potent and selective antileukemic Δ12-prostaglandin J3 (Δ12-PGJ3) is described. The convergent synthesis proceeded through intermediates 2 and 3, constructed enantioselectively from readily available starting materials and coupled through an aldol reaction followed by dehydration to afford stereoselectively the cyclopentenone alkylidene structural motif of the molecule.