A concise synthesis of (+)-botryolide-E and its C-7 epimer

Asymmetric Total Synthesis of Hasubanan Alkaloids: Periglaucines A-C, N,O-Dimethyloxostephine and Oxostephabenine

We report herein the asymmetric total synthesis of periglaucines A-C, N,O-dimethyloxostephine and oxostephabenine. The key strategies used include: 1) a Rh^I -catalyzed regio- and diastereoselective Hayashi-Miyaura reaction to connect two necessary fragments; 2) an intramolecular photoenolization/Diels-Alder (PEDA) reaction to construct the highly functionalized tricyclic core skeleton bearing a quaternary center; 3) a bio-inspired intramolecular Michael addition and transannular acetalization to generate the aza[4.4.3]propellane and the tetrahydrofuran ring.

Comprehensive Review of Recent Advances in Chiral A-Ring Flavonoid Containing Compounds: Structure, Bioactivities, and Synthesis

Flavonoids are a group of natural polyphenolic substances that are abundant in vegetables, fruits, grains, and tea. Chiral A-ring-containing flavonoids are an important group of natural flavonoid derivatives applicable in a wide range of biological activities such as, cytotoxic, anti-inflammatory, anti-microbial, antioxidant, and enzyme inhibition. The desirable development of chiral A-ring-containing flavonoids by isolation, semi-synthesis or total synthesis in a short duration proves their great value in medicinal chemistry research. In this review, the research progress of chiral A-ring-containing flavonoids, including isolation and extraction, structural identification, pharmacological activities, and synthetic methods, is comprehensively and systematically summarized. Furthermore, we provide suggestions for future research on the synthesis and biomedical applications of flavonoids.

A divergent strategy to synthesize gabosines featuring a switchable two-way aldol cyclization

Gabosines and their natural analogues, belonging to C7 carbasugars, have attracted great attention in synthesis due to their rich structural variety and promising biological activities. A new diversity-oriented approach for the gabosine-type carbasugars based on a tunable regioselective aldol cyclization of flexible precursor 2 is explored. Two cyclization modes (A and B) of the precursor can be well controlled by switching promoters to selectively produce two resulting cyclohexa(e)nones 3 and 10, both of which are versatile intermediates for various C7 carbasugars. After the conversion of 3 to eight natural carbasugars, the utility of intermediate 10 is illustrated by the first synthesis of (-)-gabosine L, as well as the new synthesis of (-)-gabosine A, (-)-gabosine B, (-)-gabosine N and (-)-gabosine O. The chemical structure and the absolute configuration of (-)-gabosine L are confirmed by its total synthesis.

Convergent Formal Synthesis of Ecteinascidin 743

A concise formal synthesis of ecteinascidin 743 is described. Key features involve the coupling of the multisubstituted tetrahydroisoquinoline and phenylalaninol moieties via a regio- and stereoselective Pictet-Spengler cyclization as well as the subsequent chemoselective MOM protection of the phenol group, which opens a rapid access to the desirable pentacycle. The synthesis successfully delivered the advanced intermediate with the characteristic macrolactone from sesamol in 23 steps.