Asymmetric Total Syntheses of (−)-Fennebricin A, (−)-Renieramycin J, (−)-Renieramycin G, (−)-Renieramycin M, and (−)- Jorunnamycin A via C–H Activation

Abstract

Collective total synthesis of five tetrahydroisoquinoline alkaloids including the first total synthesis of (−)-fennebricin A and (−)-renieramycin J has been accomplished. The synthesis features employing a single common amino acid to symmetrically construct the pentacycle of title alkaloids. The palladium-catalyzed arylation of alanine-derived amide developed by Yu was tactically utilized to afford unnatural amino acid building block rapidly and practically. The structure of synthetic (−)-renieramycin M has been confirmed by single crystal X-ray analysis for the first time.

Marine natural products

“…645 Two research groups reported the semisynthesis of the tetrahydroisoquinoline alkaloid (À)-fennebricin A (Jorunna funebris, nudibranch) starting from jorunnamycin A. 646,647 Both groups reported slight differences in several of the 1 H and 13 C NMR chemical shis and 1 H coupling constants compared to those of the isolated NP, with one group noting these differences and suggesting the need for further conrmation of the actual structure of the NP. 647 Briey highlighted in the Dinoagellate section, but just as relevant to this section, is a call for greater clarity and consistency in reporting paralytic shellsh toxin (PST, e.g.…”

Recent Advances in Radical Reactions of Vinyl Triflates and Their Derivatives

“…Li and Lu reported the synthesis of various β-ketosulfones via the ring-opening of cyclobutanone oxime ethers using vinyl triflates, both as a radical acceptor and a source of sulfur dioxide (Scheme 20 ). 28 The generated trifluoromethyl radical abstracts hydrogen from dioxane to give a radical followed by oxidation of the Cu(II) salt. The generated Cu(I) reacts with the oxime to afford an alkyl radical XI , which adds to SO 2 followed by addition to the vinyl triflate.…”

Chemical Research on Antitumor Isoquinoline Marine Natural Products and Related Compounds

“…As it has been one of the universal synthetic targets of biologically active THIQ marine natural products, to date, one semisynthesis of 50 from safracin B (6B) in six steps (24% overall yield) 60) and five total syntheses of 50 have been achieved. [61][62][63][64][65] All strategies to synthesize a characteristic pentacyclic core are based on electrophilic substitution of the electron-rich arenes, such as the modified Pictet-Spengler cyclization.…”