31. Copper on Iron: Catalyst and Scavanger for Azide-Alkzne Cycloaddition
Copper on Iron: Catalyst and Scavanger for Azide-Alkzne Cycloaddition, Szabolcs Kovács, Katalin Zih-Perényi, Ádám Révész, Zoltán Novák, Synthesis 2012; 44, 3722-3730. DOI: 10.1055/s-0032-1317697 | [Full Text Link] [Supp. Info Link]
Dipolar cycloaddition of terminal alkynes and azides catalyzed by the Cu/Fe bimetallic system is reported. In the presence of a readily accessible nanosized copper source, the cycloaddition reaction can be easily achieved at ambient temperature with high efficiency. The product obtained from the reaction catalyzed by Cu/Fe contains significantly lower copper contaminants compared to various active homogeneous copper complexes. Iron not only behaves as support for copper, but acts as a redox scavenger, and reduces the copper contamination of the organic product.
30. Design and Application of New Imidazolylsulfonate-Based Benzyne Precursor: An Efficient Triflate Alternative
Design and Application of New Imidazolylsulfonate-Based Benzyne Precursor: An Efficient Triflate Alternative, Szabolcs Kovács, Ádám I. Csincsi, Tibor Zs. Nagy, Sándor Boros, Géza Timári, Zoltán Novák, Org. Lett. 2012, 14, 2022-2025. DOI: 10.1021/ol300529j | [Full Text Link] [Supp. Info Link]
Several o-(trimethylsilyl)aryl imidazolylsulfonates were synthesized in a simple process and successfully applied in cycloadditions involving benzyne intermediates. The precursor offers an efficient alternative for generating benzynes compared to widely used ortho TMS triflates under similar reaction conditions. With the utilization of this new precursor, the formation of potentially genotoxic trifluoromethanesulfonate side product is eliminated. The applicability of the new benzyne precursor was demonstrated in different types of cycloaddition reactions to prepare heterocyclic molecules.
29. Evaluation of bis-triphenylphosphano-copper(I)-butyrate (C3H7COOCu(PPh3)2) as catalyst for the synthesis of 1-(D-glycopyranosyl)-4-substituted-1,2,3-triazoles
Evaluation of bis-triphenylphosphano-copper(I)-butyrate (C3H7COOCu(PPh3)2) as catalyst for the synthesis of 1-(D-glycopyranosyl)-4-substituted-1,2,3-triazoles, Éva Bokor, Csenge Koppány, Zsombor Gonda, Zoltán Novák, László Somsák, Carbohydr. Res. 2012, 351, 42-48. DOI: 10.1016/j.carres.2012.01.004 | [Full Text Link]
Bis-triphenylphosphano-copper(I)-butyrate (C3H7COOCu(PPh3)2) was applied for the synthesis of O-peracylated 1-glycopyranosyl-4-substituted-1,2,3-triazoles from the corresponding glycosyl azides and alkynes. This catalyst proved superior to the CuSO4/l-ascorbic acid system even with sterically hindered and less reactive glycosyl azides.
