One hundred years after the birth of Kurt Alder and seventy-five years after the discovery of his famous reaction, one of the most important and fascinating transformations in chemistry, research on that process continues to surprise, excite, delight, and inform the chemical community. This article is based on presentations given first at the University of Cologne, Germany (Kurt Alder lecture, ...

The enzyme SpnF, involved in the biosynthesis of spinosyn A, catalyzes a formal [4+2] cycloaddition of a 22-membered macrolactone, which may proceed as a concerted [4+2] Diels-Alder reaction or a stepwise [6+4] cycloaddition followed by a Cope rearrangement. Quantum mechanics/molecular mechanics (QM/MM) calculations combined with free energy simulations show that the Diels-Alder pathway is favo...

Riparian wetlands are dynamic components of landscapes. Located between uplands and aquatic environments, riparian habitats intercept sediments and nutrients before they enter aquatic environments. They are a source of organic matter and nutrients to aquatic systems, and they provide important habitat for animals, often serving as corridors for the movement of animals between habitats in fragme...

This study was aimed to determine combustion characteristics and decay resistance of Spruce [Picea orientalis (L.)], Fir (Abies nordmanniana), Alder [Alnus glutinosa (L.)], and Iroko (Milicia excelsa) woods impregnated with ammonium tetrafluoro borate (1 to 3%) and the mixture of cement and borax (6% to 9%). The combustion test method was performed in three stages: flame stage, without flame st...

The conversion of a substituted dioxinone to a pyrone was used in an improved synthesis of the AB spiroketal subunit of the spongistatins. This transformation occurred via a hetero-Diels-Alder reaction of an acyl ketene with butyl vinyl ether. A double diastereoselective Mukaiyama aldol reaction is used to provide the hetero-Diels-Alder precursor.

Synthetic access to regiodifferentiated meta-amino phenols is described. The strategy relies upon distinct deprotonation conditions to afford regioisomeric thermodynamic and kinetic dienes that undergo a tandem Diels-Alder and retro-Diels-Alder sequence with assorted acetylenic dienophiles to afford a range of aromatic products.

The total synthesis of (+)-cavicularin is described. The synthesis features an enantio- and regioselective pyrone Diels-Alder reaction of a vinyl sulfone to construct the cyclophane architecture of the natural product. The Diels-Alder substrate was prepared by a regioselective one-pot three-component Suzuki reaction of a non-symmetric dibromoarene.

New chiral sulfoxide-1,3-oxazoline ligands have been developed as chiral ligands for Lewis acid-catalyzed asymmetric Diels-Alder reactions. The use of chiral sulfinyl 1,3-oxazoline ligands in copper(II)-catalyzed asymmetric Diels-Alder reactions provided an endo cycloadduct as a major product with moderate enantioselectivity. A rationale is proposed for the mechanism of the asymmetric induction.

Diels-Alder reactions between N-phenylmaleimide, acting as the dienophile, and 2(1H)-pyridones having a methoxy or a chloro substituent, were carried out, under atmospheric and high pressure conditions, to give the corresponding isoquinuclidine derivatives. Stereoselectivity of the Diels-Alder reactions was studied using molecular orbital calculations.