Synthesis of saframycins. X. Transformation of (-)-saframycin A to (-)-saframycin Mx type compound with the structure proposed for saframycin E

Transformation of Renieramycin M into Renieramycins T and S by Intramolecular Photoredox Reaction of 7-Methoxy-6-methyl-1,2,3,4-tetrahydroisoquinoline-5,8-dione Derivatives

In connection with our studies of biologically active 1,2,3,4-tetrahydroisoquinoline marine natural products, we describe herein a useful intramolecular photoredox transformation of 7-methoxy-6-methyl-1,2,3,4-tetrahydroisoquinoline-5,8-dione tricyclic models into 5-hydroxy-tetrahydroisoquinol[1,3]dioxoles in excellent yields. We applied this methodology to the transformation of renieramycin M into renieramycins T and S and the transformation of saframycin A. The results of cytotoxicity studies are also presented.

Dearomative logic in natural product total synthesis

Covering: 2011 to 2022The natural world is a prolific source of some of the most interesting, rare, and complex molecules known, harnessing sophisticated biosynthetic machinery evolved over billions of years for their production. Many of these natural products represent high-value targets of total synthesis, either for their desirable biological activities or for their beautiful structures outright; yet, the high sp3-character often present in nature's molecules imparts significant topological complexity that pushes the limits of contemporary synthetic technology. Dearomatization is a foundational strategy for generating such intricacy from simple materials that has undergone considerable maturation in recent years. This review highlights the recent achievements in the field of dearomative methodology, with a focus on natural product total synthesis and retrosynthetic analysis. Disconnection guidelines and a three-phase dearomative logic are described, and a spotlight is given to nature's use of dearomatization in the biosynthesis of various classes of natural products. Synthetic studies from 2011 to 2021 are reviewed, and 425 references are cited.

Chemical Research on Antitumor Isoquinoline Marine Natural Products and Related Compounds

The biologically active, naturally occurring 1,2,3,4-tetrahydroisoquinoline-quinone (THIQ) family members isolated from Actinomycetes and marine organisms have been studied thoroughly over the past five decades. Among them, marine natural products along with their reduced compounds, such as renieramycins and ecteinascidins, have attracted interest due to their fantastic structures and meager availability in nature as well as their potent antitumor profiles. As part of our search for new anticancer metabolites through the isolation and characterization of anticancer THIQ compounds from Thai marine animals, we have developed a fascinating THIQ natural product chemistry and medicinal chemistry based on knowledge of the chemistry of saframycin antibiotics as well as their isolation, characterization, transformation, partial synthesis, and total synthesis. This review mainly presents our contributions during 1999-2019 to the field of research on biologically active renieramycin along with ecteinascidin marine natural products.

Synthesis and cytotoxic evaluation of some cribrostatin-ecteinascidin analogues

Analogues of cribrostatin IV ( 1) and the potent antineoplastic agent ecteinascidin 743 ( 2) have been synthesized. The cytotoxic activity of these compounds ( 5, 14, 20) has been determined, and the cyanoamine-cribrostatin analogue ( 14) exhibits a 20-fold improvement with regard to the natural product 1.

Total Synthesis of Cribrostatin IV: Fine-Tuning the Character of an Amide Bond by Remote Control

We report the enantioselective total synthesis of cribrostatin IV (1). Key features of this synthesis involve the convergent coupling of two highly functionalized homochiral components followed by a "lynchpin" Mannich cyclization to establish the pentacyclic core (cf. 19 --> 20).

Renieramycin J, a highly cytotoxic tetrahydroisoquinoline alkaloid, from a marine sponge Neopetrosia sp

Renieramycin J (1), a new tetrahydroisoquinoline alkaloid, has been isolated from a marine sponge Neopetrosia sp. as a potent cytotoxin that induced morphological changes in 3Y1 cells. Such changes are characteristic of RNA and/or protein synthesis inhibitors. The structure of 1 including the absolute stereochemistry was determined by spectroscopic and chemical methods.

Antineoplastic agents 430. Isolation and structure of cribrostatins 3, 4, and 5 from the republic of maldives cribrochalina species

Continued investigation of cancer-cell growth-inhibitory constituents of the blue marine sponge Cribrochalina sp. has led to discovery of cribrostatins 3 (4a), 4 (5), and 5 (4b) in 10(-5) to 10(-7) % of the wet weight. The structure of cribrostatin 3 (4a) was determined by results of high field (500 MHz) (1)H and (13)C NMR and HRMS interpretations. The same general approach to the structures of cribrostatins 4 (5) and 5 (4b) was completed by X-ray crystal structure determinations. Cribrostatins 3, 4, and 5 provided significant cancer cell line inhibitory activities. Cribrostatins 1 and 2(2) and the newly isolated cribrostatins 3-5 displayed antibacterial and/or antifungal activities.