Asymmetric synthesis, stereochemistry and rearrangement reactions of naturally occurring 7′-hydroxylignano-9,9′-lactones

Abstract

The asymmetric synthesis of a series of (7'S,8R,8'R)-7'-hydroxylignano-9,9'-lactones is presented, among them the mammalian lignan (7'S)-hydroxyenterolactone and (7'S)-parabenzlactone, allowing the stereochemistry of natural occurring (-)-parabenzlactone to be re-assigned. A hydroxylactone rearrangement and its possible mechanisms are discussed. Finally a brief survey of the current naming and numbering variants of 7'-hydroxylignano-9,9'-lactones is presented, along with a suggestion for harmonization of the nomenclature.

Artemyrianins A–G from Artemisia myriantha and Their Cytotoxicity Against HepG2 Cells

“…By comparing their 1 H and 13 C NMR (DEPT) spectroscopic data with those reported in literatures, five known compounds were identified as (−)-hinokinin ( 8 ) [ 18 ], (8 R ,8′ R )-4,4′,5,5′-bis(methylenedioxy)-7′-oxolignano-9,9′-lactone ( 9 ) [ 19 ], isofraxidin ( 10 ) [ 20 ], dracunculin ( 11 ) [ 21 ] and 5-acetyl-6-hydroxy-2-(1-hydroxy-1-methylethyl)benzofuran ( 12 ) [ 22 ], respectively.…”

Phosphine‐Free Palladium‐Catalyzed Allene Carbopalladation/Allylic Alkylation Domino Sequence: A New Route to 4‐(α‐Styryl) γ‐Lactams

“…[15] The pyrrolidin-2-one 13 was first submitted to demethoxycarbonylation [16] to yield the expected g-lactam 17 in 92 % yield. Functionalization at position 3 using lithium 2,2,6,6-tetramethylpiperidide (LiTMP), hexamethylphosphoramide (HMPA), and piperonyl bromide afforded the expected benzylated lactam 18 in 75 % yield as a single trans diastereoisomer.…”

Design and Synthesis of a Compound Library Exploiting 5-Methoxyleoligin as Potential Cholesterol Efflux Promoter

“…Hence, within a multi-disciplinary project on the identification of natural products with anti-inflammatory activity [6], developing a fast, high yielding, and modular chemical synthesis of 5-methoxyleoligin and leoligin was tackled. Although there are various lignan syntheses in the scientific literature [11][12][13][14][15] delivering scaffolds with the correct absolute configuration in enantiomerically pure form, 5-methoxyleoligin was never a target of one of these syntheses and was not obtained synthetically so far. One important reason for that is that those approaches were relatively long and not modular enough to quickly access another related compound apart from the targeted molecule.…”