The aerial parts of Achillea setacea afforded, in addition of a rare monoterpene triol and 12 known sesquiterpene lactones, a new guaianolide containing an endoperoxide ring. Its structure was elucidated by spectral methods.

This article summarizes the recent developments (particularly the uses of homogeneous organometallic catalysts) in ring-opening carbonylations, ring-opening carbonylative polymerizations and ring-expansion carbonylations of heterocycles such as epoxides, aziridines, lactones and oxazolines.

N-Acylhomoserine lactones (AHLs) are quorum sensing signals produced by Gram-negative bacteria. We here report the affinity purification of AHL synthases using beads conjugated with an enzyme inhibitor, which was designed based on the catalytic intermediate acyl-SAM.

The enantioselective N-heterocyclic carbene-catalyzed [4 + 2] cyclocondensation of 2-aryl carboxylic acids and enones was developed, affording the corresponding chiral δ-lactones in good yields with good diastereo- and high enantioselectivities.

A catalytic amount of TEMPO in the presence of PhI(OAc)(2) effected oxidative lactonization of 1,6- and 1,7-diols, directly affording seven- and eight-membered lactones, respectively, in good yields.

The macrocyclic lactones are the biggest selling and arguably most effective anthelmintics currently available. They are good substrates for the P-glycoproteins, which might explain their selective toxicity for parasites over their vertebrate hosts. Changes in the expression of these pumps have been implicated in resistance to the macrocyclic lactones, but it is clear that they exert their anth...

The most recent phase of the work on simple carbohydrates is concerned with isomerisms occasioned by differences in size of the oxidic ring. The first observations which brought to light the existence of such isomers were made by Nef’ and by E. Fischer.2 Nef discovered two isomeric galactonic lactones and Fischer a third isomer of l-methyl glucose. Isomers of this type have been discovered for ...

Of all plant constituents, coffee has one of the highest concentrations of chlorogenic acids. When roasting coffee, some of these are transformed into chlorogenic acid lactones (CGL). We have studied the formation of CGL during the roasting of coffee beans in Coffea arabica cv. Bourbon; C. arabicacv. Longberry; and C. canephora cv. Robusta. Individual CGL levels were determined by comparison of...

An investigation of the reaction requirements to effect the Clauson-Kaas pyrrole synthesis led to the formulation of a new procedure that avoids the contact of pyrroles to heat or strongly acidic conditions that cause decomposition of the desired products. The procedure involves mild hydrolysis of 2,5-dimethoxytetrahydrofuran in water to the activated species 2,5-dihydroxytetrahydrofuran that r...

Pro-Val pseudo dipeptides incorporating protio and halo enol lactones were tested for inhibitory activity against the serine proteases human leukocyte elastase (HLE), porcine pancreatic elastase, alpha-chymotrypsin, trypsin, thrombin, and urokinase. The protio enol lactones 1a-c were found to be HLE substrates but were poor alternate substrate inhibitors. The bromo enol lactone trans isomer 2a ...