227454-51-5Relevant articles and documents
Stable Pyrrole-Linked Bioconjugates through Tetrazine-Triggered Azanorbornadiene Fragmentation
Bernardes, Gon?alo J. L.,Corzana, Francisco,Gil de Montes, Enrique,Hoyt, Emily A.,Istrate, Alena,Jiménez-Moreno, Ester,Jiménez-Osés, Gonzalo,Moreno-Vargas, Antonio J.,Navo, Claudio D.,Robina, Inmaculada
, p. 6196 - 6200 (2020)
An azanorbornadiene bromovinyl sulfone reagent for cysteine-selective bioconjugation has been developed. Subsequent reaction with dipyridyl tetrazine leads to bond cleavage and formation of a pyrrole-linked conjugate. The latter involves ligation of the tetrazine to the azanorbornadiene-tagged protein through inverse electron demand Diels–Alder cycloaddition with subsequent double retro-Diels–Alder reactions to form a stable pyrrole linkage. The sequence of site-selective bioconjugation followed by bioorthogonal bond cleavage was efficiently employed for the labelling of three different proteins. This method benefits from easy preparation of these reagents, selectivity for cysteine, and stability after reaction with a commercial tetrazine, which has potential for the routine preparation of protein conjugates for chemical biology studies.
Organocatalytic asymmetric direct α-alkynylation of cyclic β-ketoesters
Poulsen, Thomas B.,Bernardi, Luca,Aleman, Jose,Overgaard, Jacob,Jorgensen, Karl Anker
, p. 441 - 449 (2007/10/03)
The first organocatalytic enantioselective direct α-alkynylation of β-ketoesters and 3-acyl oxindoles is described. It is demonstrated that activated β-halo-alkynes undergo nucleophilic acetylenic substitution catalyzed by chiral phase-transfer compounds to afford the alkynylated products in high yields and excellent enantioselectivities. The potential of the reaction is first demonstrated for various alkynylating reagents having chloride and bromide as the leaving groups and substituents such as allyl and alkyl esters, amides, ketones, and sulfones. These reactions proceed with 74-99% yield and 88-97% ee. Then the scope in nucleophile is demonstrated for a large number of cyclic β-ketoesters with various ring-sizes and for oxindoles as well. The corresponding optically active products are formed in high yields and with enantioselectivities up to 98% ee. The procedure allows for the stereocontrolled attachment of an ethynyl unit in the α-position to the carbonyl compound by facile removal of the activating group, and this has been demonstrated for a number of the optically active allyl esters. Furthermore, the synthesis of optically active 1,4-enynes is also shown. The isolation and characterization by X-ray analysis of the catalyst with p-nitrophenolate as the counterion allowed us to propose a model of the catalyst-substrate intermediate which might account for the observed enantioselectivity of the organocatalytic enantioselective α-alkynylation reaction. Furthermore, it is suggested that this intermediate is also the reactive species for a number of other electrophiles adding to β-ketoesters giving enantioselectivities in the range of 90-98% ee.
2-Bromoethynyl aryl sulfones as versatile dienophiles: A formal synthesis of epibatidine
Zhang, Chunming,Ballay II, Charles J.,Trudcll, Mark L.
, p. 675 - 676 (2007/10/03)
A facile synthesis of 2-bromoethynyl aryl sulfones has been developed; the reactivity of these versatile dienophiles in [4 + 2] cycloaddition reactions as well as application in a formal synthesis of epibatidine is described.
