Novel asymmetric syntheses of (−)-malyngolide and (+)-epi-malyngolide

Investigation of the Anti-Methicillin-Resistant Staphylococcus aureus Activity of (+)-Tanikolide- and (+)-Malyngolide-Based Analogues Prepared by Asymmetric Synthesis

Herein, we report antibacterial and antifungal evaluation of a series of previously prepared (+)-tanikolide analogues. One analogue, (4S,6S)-4-methyltanikolide, displayed promising anti-methicillin-resistant Staphylococcus aureus activity with a MIC of 12.5 µg/mL. Based on the antimicrobial properties of the structurally related (-)-malyngolide, two further analogues (4S,6S)-4-methylmalyngolide and (4R,6S)-4-methylmalyngolide bearing a shortened n-nonyl alkyl side chain were prepared in the present study using a ZrCl₄-catalysed deprotection/cyclisation as the key step in their asymmetric synthesis. When these were tested for activity against anti-methicillin-resistant Staphylococcus aureus, the MIC increased to 50 µg/mL.

A retro Baeyer-Villiger reaction: electrochemical reduction of [60]fullerene-fused lactones to [60]fullerene-fused ketones

An unprecedented retro Baeyer–Villiger reaction has been achieved by the electrochemical reduction of [60]fullerene-fused lactones in the presence of acetic acid at room temperature, affording [60]fullerene-fused ketones in excellent yields within a short time.

A highly efficient electrochemical reduction of [60]fullerene-fused lactones to [60]fullerene-fused ketones, a formal process of retro Baeyer–Villiger reaction, has been achieved for the first time. The electrochemically generated dianionic [60]fullerene-fused lactones can be transformed into [60]fullerene-fused ketones in the presence of acetic acid in 85–91% yields. Control experiments have been performed to elucidate the reaction mechanism. The products have been characterized with spectroscopic data and single-crystal X-ray analysis. Moreover, the electrochemical properties have also been investigated.

Converting cycloalkanones into N-heterocycles: formal synthesis of (-)-gephyrotoxin 287C

The photochemical rearrangement of N-activated lactams enables their ring contraction concomitant with the migration of a carbon onto a nitrogen atom. When coupled with the Beckmann rearrangement, this photochemical ring contraction converts cycloalkanones into N-heterocycles in a few steps and in a stereospecific manner. To showcase the method, we performed an efficient formal synthesis of (-)-gephyrotoxin 287C.

A short, stereoselective, and common approach for the synthesis of 4,5-disubstituted delta-lactones simplactone B and its C-5 analogue

A short, stereoselective, and a common approach for the synthesis of 4,5-disubstituted delta-lactones simplactone B and its analogue using Evans protocol is described.

Asymmetric Carroll rearrangement of allyl α-acetamido-β-ketocarboxylates catalysed by a chiral palladium complex

Asymmetric decarboxylative rearrangement (Carroll rearrangement) of allyl alpha-acetamido-beta-ketocarboxylates was catalysed by a palladium complex modified with a chiral phosphine ligand, giving optically active gamma,delta-unsaturated alpha-aminoketones with up to 90% ee.

Asymmetric hetero Diels-Alder route to quaternary carbon centers: synthesis of (-)-malyngolide

Conformationally constrained chiral bis(oxazoline)-metal complex catalyzed asymmetric hetero Diels-Alder reactions of Danishefsky's diene and a variety of α-keto esters constructed quaternary carbon centers enantioselectively. The reaction was utilized in the synthesis of (-)-malyngolide.