Two metal-free, formal [2 + 2 + 2] cycloaddition strategies for the construction of polycyclic pyridine derivatives are described that proceed via pericyclic cascade mechanisms featuring the participation of unactivated cyano groups as enophile and dienophile cycloaddition partners.

An asymmetric gold(I)-catalyzed [3+2] cycloaddition of propargyl acetals/ketals and aldehydes is reported, which proceeds via stepwise migration-fragmentation of acetals/ketals and cycloaddition of the in situ generated gold-carbenoid intermediate. Various functionalized 2, 5-dihydrofurans were obtained in good yields and high enantioselectivities. Furthermore, an example of the first gold(I) c...

Oxadiazolones are first employed as the three-atom coupling partners in the Tf2NH-catalyzed cycloaddition with ynamides. This formal [3 + 2] cycloaddition allows a rapid synthesis of aminoimidazoles with a broad substrate scope. The approach also features a metal-free catalytic cycloaddition process, which may find applications in the synthesis of bioactive molecules. Besides, the resulting N-m...

in this paper the synthesis of some new polyaromatic monocyclic β-lactams has been reported. these cycloadducts have been synthesized by the [2+2] ketene-imine cycloaddition reaction known as the staudinger reaction. all of the products have been fully characterized by ir, 1h-nmr, 13c-nmr, mass spectroscopy and elemental analyses. the x-ray crystal structure of a cis β-lactam has been also pres...

We report an assay for determining the number of fluorophores conjugated to single plasmid DNA molecules and apply this to compare the efficiency of fluorophore coupling strategies for covalent DNA labelling. We compare a copper-catalyzed azide-alkyne cycloaddition reaction, amine to N-hydroxysuccinimidyl ester coupling reaction and strain-promoted azide-alkyne cycloaddition reaction for fluore...

Gas-phase reactions of acylium ions with alpha,beta-unsaturated carbonyl compounds were investigated using pentaquadrupole multiple-stage mass spectrometry. With acrolein and metacrolein, CH(3)-C(+)(double bond)O, CH(2)(double bond)CH-C(+)(double bond)O, C(6)H(5)-C(+)(double bond)O, and (CH(3))(2)N-C(+)(double bond)O react to variable extents by mono and double polar [4 + 2(+)] Diels-Alder cycl...

ortho-Quinone methides, arising from a formal [2+2] cycloaddition between arynes and DMF, were found to facilely undergo a [4+2] cycloaddition with ester enolates or ketenimine anions to produce diverse coumarins in a straightforward manner.

Osmate-exchanged Mg-Al layered double hydroxides catalysed the delivery of two oxygen atoms simultaneously via a 3 + 1 cycloaddition to sulfide to form sulfone directly for the first time, reminiscent of 3 + 2 cycloaddition in asymmetric dihydroxylation reactions.

The combination of two or more unsaturated structural units to form cyclic organic compounds is commonly referred to as cycloaddition, and the combination of two unsaturated structural units that forms a six-membered ring is formally either a [5 + 1]-, [4 + 2]-, [2 + 2 + 2]-, or [3 + 3]-cycloaddition. Occurring as concerted or stepwise processes, cycloaddition reactions are among the most usefu...

Microcontact printing (μCP) has developed into a powerful tool to functionalize surfaces with patterned molecular monolayers. μCP can also be used to induce a chemical reaction between a molecular ink and a self-assembled monolayer (SAM) in the nanoscale confinement between stamp and substrate. In this paper, we investigate the Huisgen 1,3-dipolar cycloaddition, the Diels-Alder cycloaddition an...