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Hafnium trifluoromethanesulfonate is a recyclable catalyst for the mononitration of o-nitrotoluene. It serves as a catalyst for homogeneous methoxycarbonylation and hydrocarboxylation reactions of phenylacetylene. It is also used as a reactant for direct Friedel-Crafts reactions of chromene hemiacetals, aminomethylation reactions under Lewis acidic conditions and prins-type cyclization reactions. It is also involved in the direct polycondensation of lactic acid. Further, it is used in cationic benzylation reactions, chemoselective thioacetalization and transthioacetalization of carbonyl compounds.
Lewis acid catalyst introduced by Kobayashi, effective at low concentrations under mild conditions in Friedel-Crafts acylation and alkylation reactions: Bull. Chem. Soc. Jpn., 68, 2053 (1995). Efficient catalyst for the Fries rearrangement of phenolic esters to acylphenols: Tetrahedron Lett., 37, 2053 (1996); Bull. Chem. Soc. Jpn., 70, 267 (1997). Superior to lanthanide triflates as catalyst for atom-economic aromatic nitration with a stoichiometric amount of nitric acid in DCM, avoiding the use of sulfuric acid: Tetrahedron Lett., 39, 1641 (1198); Synlett, 57 (2000). Efficient catalyst for allylations of imines with Allyltri-n-butyltin, L14087, and of Mannich-type reactions of imines with silyl enol ethers: Synlett, 1099 (1997). For use in combination with a catalytic amount of triflic acid for the Friedel-Crafts acylation of aromatics, see: Tetrahedron Lett., 39, 4697 (1998). For use in the catalytic decarboxylative ß-selective glycosylation via a mixed glycosyl carbonate, see: Synlett, 959 (2004). Catalyzes the conjugate addition of indoles to ɑß-enones: Synlett, 2492 (2005).
Ishitani, H.; Suzuki, H.; Saito, Y.; Yamashita, Y.; Kobayashi, S. Hafnium Trifluoromethanesulfonate [Hf(OTf)4] as a Unique Lewis Acid in Organic Synthesis. Eur. J. Org. Chem. 2015, 2015 (25), 5485-5499.
Adams, T. C.; Payette, J. N.; Cheah, J. H.; Movassaghi, M. Concise Total Synthesis of (+)-Luteoalbusins A and B. Org. Lett. 2015, 17 (17), 4268-4271.
Dichiarazioni di rischio (UE): H315-H319-H335
Causes skin irritation. Causes serious eye irritation. May cause respiratory irritation.
Dichiarazioni precauzionali: P261-P280a-P305+P351+P338-P304+P340-P405-P501a
Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves and eye/face protection. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. IF INHALED: Remove to fresh air and keep at rest in a position comfortable for breathing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.