Scandium trifluoromethanesulfonate (Sc(OTf)3). A novel reusable catalyst in the Diels-Alder reaction

Diels–Alder Reaction of Cyclopentadiene and Alkyl Acrylates in the Presence of Pyrrolidinium Ionic Liquids with Various Anions

“…A good solubility of the catalysts has been of crucial importance in their applications. The catalysts of these cycloaddition reactions are frequently trifluoromethanesulfonates and chlorides of the rare-earth elements such as: M(OTf) 3 , MCl 3 (M = Sc, La, Ce, Y, OTf ¼ CF 3 SO 3 À ) [10][11][12][13][14][15][16][17][18][19]. The ionic liquids used in this type of reaction include the salts containing imidazolium [20], pyridinium [21], phosphonium [22] cation and bis(trifluoromethylsulfonyl)imide as the anion.…”

Lanthanide Formamidinates as Improved Catalysts for the Tishchenko Reaction

“…These properties, which can be finetuned by variation of the ionic radius of the lanthanide cation, are the driving force for various catalytic processes. [2] Thus, lanthanide triflates [Ln(OTf) 3 ] turned out to be very active catalysts for aldol, [3] Michael, [4] allylation, [5] Diels-Alder, [6] and glycosylation reactions [7] , as well as for Friedel-Crafts acylations. [8,9] Lanthanide alkoxides [Ln(OR) 3 ] have proven to be useful catalysts for the Meerwein-Ponndorf-Verley reduction [10] and for hydrocyanation, [11] whereas lanthanide shift reagents such as Eu(fod) 3 (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate) can be used as catalysts for Diels-Alder [12] and hetero-Diels-Alder reactions.…”

“…K 2 [Fe(CO) 4 ]). [26] Scheme 6 ] (tBu 2 pz = 3,5-di-tert-butylpyrazolate) can be readily prepared from La metal and the appropriate pyr-azole. [15] Furthermore, very recently the homoleptic bis-(trimethylsilyl)amides of the alkaline earth metals [M{N(SiMe 3 ) 2 } 2 ] (M = Ca, Sr, Ba) were reported as precatalysts for the Tishchenko reaction, and they are almost as active as the lanthanide compounds.…”

Diels-Alder reactions in aqueous media

“…This Lewis-acid-catalyzed aqueous Diels-Alder reaction presumably occurs via a transition state such as 2.50 with bidentate complexation to the metal as shown. In a related study, Kobayashi reported that scandium trifiate can be used as a water-tolerant Lewis-acid catalyst for a Diels-Alder reaction in (9:1) tetrahydrofuran-water (THF-H20) [30], though this mixed solvent system cannot take advantage of the hydrophobic effect observed in pure water or highly aqueous mixtures.…”