https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Isatins As Privileged Molecules in Design and Synthesis of Spiro-Fused Cyclic Frameworks

The asymmetric organocatalysis is definitely one of the most powerful and versatile tools for the rapid construction of various spirocyclic oxindoles. In the past few years, a number of successful strategies based on organocatalysis have been developed for the construction of 3,3′-spirocyclic oxindoles in high yields and excellent enantioselectivities under mild conditions. In this review, recent advances in this area are summarized and classified according to the spiro ring fused at the 3-position of the oxindole core.

Recent Advances in Asymmetric Organocatalytic Construction of 3,3′-Spirocyclic Oxindoles

In this critical review the applications of gold catalysed reactions in total synthesis during the years since our last article are reviewed. At the end of this article a literature analysis is conducted to evaluate the progress in this field.

Gold catalysis in total synthesis – recent achievements

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

[Structure: see text]. Citrinadin A (2) is a pentacyclic indolinone alkaloid isolated from the cultured broth of a fungus, Penicillium citrinum, which was separated from a marine red alga. The absolute stereochemistry of the pentacyclic core in 2 and its new congener, citrinadin B (1), was elucidated by analysis of the ROESY spectrum for the chlorohydrin derivative (3) of 1 as well as comparison of the electronic circular dichroism (ECD) spectra for 1 and 2 with those of known spirooxiindole alkaloids. On the other hand, the absolute configuration at C-21 bearing an epoxide ring was assigned as S by comparison of the vibrational circular dichroism (VCD) spectra of 1 with those of model compounds 2S- and 2R-2,3-epoxy-3,3-dimethyl-1-phenylpropan-1-one (4a and 4b, respectively).

Absolute stereochemistry of citrinadins a and B from marine-derived fungus.

Citrinadin A, a novel pentacyclic alkaloid from marine-derived fungus Penicillium citrinum.

Two new cytotoxic twelve-membered macrolides, sporiolides A (1) and B (2), were isolated from the cultured broth of a fungus Cladosporium sp., which was separated from an Okinawan marine brown alga Actinotrichia fragilis, and the structures were elucidated by spectroscopic data. Sporiolides A (1) and B (2) exhibited cytotoxicity against murine lymphoma L1210 cells. Spoliolide A (1) showed antifungal activity against Cryptococcus neoformans and Neurospora crassa.

https://www.mdpi.com/1660-3397/2/4/164/pdf

Sporiolides A and B, New Cytotoxic Twelve-Membered Macrolides from a Marine-Derived Fungus Cladosporium Species

A new polyketide glycoside, cladionol A (1), was isolated from the cultured broth of a fungus Gliocladium sp., which was separated from sea grass Syringodium isoetifolium, and the structure was elucidated by spectroscopic data. The relative stereochemistry of C-2-C-3 was assigned by mainly J-based configuration analysis, while those of two sugar units were elucidated to be beta-mannopyranoside and arabitol on the basis of NOESY data and/or 1H-1H couplings. Furthermore, the absolute configuration of the mannose moiety was determined as the D-form on the basis of chiral HPLC analysis of a benzoyl derivative of the acid hydrolysate of 1. Cladionol A (1) exhibited modest cytotoxicity.

Yuu Kasai

Papers

Absolute stereochemistry of citrinadins a and B from marine-derived fungus.

Citrinadin A, a novel pentacyclic alkaloid from marine-derived fungus Penicillium citrinum.

Sporiolides A and B, New Cytotoxic Twelve-Membered Macrolides from a Marine-Derived Fungus Cladosporium Species

Cladionol A, a Polyketide Glycoside from Marine-Derived Fungus Gliocladium Species

Absolute Stereochemistry of Citrinadins A (Ia) and B (Ib) from Marine-Derived Fungus.