Syntheses of methylenolactocin and nephrosterinic acid via diastereoselective acylation and chemoselective reduction–lactonization

Synthesis and application of methyl itaconate-anthracene adducts in configuration assignment of chiral secondary alcohols by 1H NMR

Novel chiral derivatising agents (CDAs) such as methyl itaconate-anthracene adducts (MIAs) were reported for the absolute configuration determination of chiral secondary alcohols by the ¹H NMR technique. These adducts were facilely prepared through well-known reactions, and furthermore, commercially available starting materials. According to these synthetic routes, the desired MIAs were afforded in 6 steps with 49% overall yield from dimethyl itaconate. Moreover, the represented MIAs provided significantly large differences of chemical shift values (Δδ^SR). No racemisation from the tertiary characteristics of the adjacent alpha carbon was observed.

An efficient enantioselective approach to multifunctionalized γ-butyrolactone: concise synthesis of (+)-nephrosteranic acid

A short, efficient and novel approach for multifunctionalized γ-butyrolactone paraconic acids and its application to the total synthesis of (+)-nephrosteranic acid from readily available PMB (R)-glycidyl ether as a starting material are described. Key transformations include asymmetric Michael addition catalyzed by chiral diphenylprolinol silyl ether and stereoselective α-methylation.

Synthesis and characterization of novel chiral derivatizing agents containing β-keto-anthracene adducts (KAAs) by 1H-NMR: aromatic influence and chiral alcohol absolute configuration determination

New chiral derivatizing agents and the effect of aromatic rings were investigated for absolute configuration of chiral alcohols via¹H-NMR.

A protecting-group-free synthesis of (+)-nephrosteranic, (+)-protolichesterinic, (+)-nephrosterinic, (+)-phaseolinic, (+)-rocellaric acids and (+)-methylenolactocin

A collective synthesis of a γ-butyrolactone class of paraconic acids such as (+)-methylenolactocin, (+)-phaseolinic acid, (+)-nephrosteranic acid, (+)-nephrosterinic acid, (+)-rocellaric acid and (+)-protolichesterinic acid is described.

Enzymatic resolution of α-methyleneparaconic acids and evaluation of their biological activity

Both enantiomers of three biologically relevant paraconic acids-MB-3, methylenolactocin, and C75-were obtained with enantioselectivities up to 99% by kinetic enzymatic resolutions. Good enantiomeric excesses were obtained for MB-3 and methylenolactocin, using α-chymotrypsin and aminoacylase as enantiocomplementary enzymes, while C75 was resolved with aminoacylase. They all were evaluated for their antiproliferative, antibacterial, and antifungal activities, showing weak effects and practically no difference between enantiomers in each case. At high concentrations (16-64 µg/mL), (-)- C75 acted as an antimicrobial agent against Gram-positive bacteria.

Butyrolactone synthesis via polar radical crossover cycloaddition reactions: diastereoselective syntheses of methylenolactocin and protolichesterinic acid

A direct catalytic synthesis of γ-butyrolactones from simple alkene and unsaturated acid starting materials is reported. The catalytic system consists of the Fukuzumi acridinium photooxidant and substoichiometric quantities of a redox-active cocatalyst. Oxidizable alkenes such as styrenes and trisubstituted aliphatic alkenes are cyclized with unsaturated acids via polar radical crossover cycloaddition (PRCC) reactions. This method has been applied to the diastereoselective total synthesis of methylenolactocin and protolichesterinic acid.