The key steps in the synthesis of clavulactone are formation of an enantiopure cyclopentane precursor by epoxide rearrangement and intramolecular carbonyl-ene reaction, construction of the 3,4-dihydro-2H-pyran ring by intermolecular hetero-Diels-Alder reaction, closure of the eleven-membered ring, and finally generation of the lactone functionality by chemoselective allylic C(sp(3))-H oxidation.

We have found that some of the usually poor dienophiles (2-cycloenones) can undergo Diels-Alder reaction at -78 degrees C with unusually high stereoselectivity in the presence of niobium pentachloride as a Lewis acid catalyst. A remarkable difference in reaction rates for unsubstituted and alpha- or beta-methyl substituted 2-cycloenones was also observed.

The efficiency of the Photo-Dehydro-Diels-Alder (PDDA) reaction was considerably improved by triplet sensitization using xanthone. This allowed use UVA lamps as light source, which have a markedly higher output compared with previously used UVB lamps. In combination flow photochemistry PDDA is powerful method for total synthesis arylnaphthalen lignans.

A highly enantioselective, quinone Diels-Alder reaction catalyzed by chiral samarium and gadolinium pyridyl-bis(oxazoline) (pybox) complexes has been developed. The reaction scope has been extended to include three quinones and five dienes, all of which exclusively provide the expected endo product in excellent yields and enantioselectivities.

With a miniaturized (3 microL volume) fiber-optics based system for on-line measurement by UV/Vis spectroscopy, the reaction rate constants (at different pressures) and the activation volumes (deltaV(not =)) were determined for a nucleophilic aromatic substitution and an aza Diels-Alder reaction in a capillary microreactor.

[2,5-Dimethylfuran]-protected maleimides were placed at both internal positions and the 3'-end of oligonucleotides making use of solid-phase synthesis procedures. A new phosphoramidite derivative and a new solid support incorporating the protected maleimide moiety were prepared for this purpose. In all cases maleimide deprotection (retro-Diels-Alder reaction) followed by reaction with thiol-con...

A new synthetic route to indeno[1,2-b]quinolines via reactions of o-propargylbenzaldehydes with N-aryl amines based on an intramolecular aza-Diels-Alder (Povarov) reaction has been developed. This method offers several advantages such as no requirement for an oxidant, high efficiency, and a wide reaction scope.