The furan-maleimide Diels-Alder chemistry has emerged as an important tool to design thermo-reversible click networks. This not only preserves the strong and robust properties of thermo-sets rubbers, but also makes it possible cleave crosslinks at non-degradative temperatures, or in other words recycle them. In this work a new reaction is reported networks, which Double-Diels-Alder (DDA), known...

The daily pollen counts in the air of Seoul, Korea were measured using a rotorod sampler from June 1990 to July 1992. Two distinct pollen periods were noted: tree pollens such as alder, poplar, willow, oak and pine appeared in the spring from March to May, and weed pollens, such as Artemisia spp., Ambrosia spp. and Hop japanese appeared in the autumn from August to September. Various kinds of g...

The synthesis of silaheterocycles through the first examples of an intramolecular silene Diels-Alder reaction is described.

Bromoenynamides represent precursors to a diversity of azacycles by a cascade sequence of carbopalladation followed by cross-coupling/electrocyclization, or reduction processes. Full details of our investigations into intramolecular ynamide carbopalladation are disclosed, which include the first examples of carbopalladation/cross-coupling reactions using potassium organotrifluoroborate salts; a...

2-Silicon-substituted 1,3-dienes containing non transferrable groups known to promote transmetallation were prepared by Grignard chemistry and enyne metathesis. These dienes participated in one pot metathesis/Diels-Alder reactions in regio- and diastereoselective fashions. Electron-rich alkenes showed the fastest rates in metathesis reactions, and ethylene, a commonly used metathesis promoter s...

Diels-Alder cycloaddition between cyclopentadiene and p-benzoquinone has been studied in the confined space of a pure silica zeolite Beta and the impact on reaction rate due to the concentration effect within the pore and diffusion limitations are discussed. Introduction of Lewis or Brønsted acid sites on the walls of the zeolite strongly increases the reaction rate. However, contrary to what o...

In 1956, Alder conjectured that the number of partitions of n into parts differing by at least d is greater than or equal to that of partitions of n into parts ≡ ±1 (mod d + 3). The Euler identity, the first Rogers-Ramanujan identity, and a theorem of Schur show that the conjecture is true for d = 1, 2, 3, respectively. In 1971, Andrews proved that the conjecture holds for d = 2 − 1, r ≥ 4. In ...

Chiral diamine-derived hydrogen-bond donors were evaluated for their ability to effect stereocontrol in an intramolecular hetero-Diels-Alder (HDA) reaction hypothesized in the biosynthesis of brevianamides A and B. Collectively, these results provide proof of principle that small-molecule hydrogen-bond catalysis, if even based on a hypothetical biosynthesis construct, holds significant potentia...

Enynes connected through aromatic rings are used as substrates for metathesis reactions. The reactivity of three ruthenium carbene complexes is compared. The resulting 1,3-dienes are suitable precursors of polycyclic structures via a Diels-Alder process. Some domino RCM-Diels-Alder reactions are performed, suggesting a possible beneficial effect of the ruthenium catalyst in the cycloaddition pr...

The chemical crosslinking of modified nucleic acids via the Diels-Alder reaction is reported. For this purpose, 1,3-butadiene derived building blocks were incorporated into complementary oligodeoxynucleotides. Treatment of the obtained duplex with difunctional dienophiles results in the clean crosslinking of the two strands. Non-crosslinked adducts arising from a single Diels-Alder reaction of ...