(P₂O₅/SiO₂): A Useful Heterogeneous Alternative for the Ritter Reaction.

Abstract

Amide formation O 0325 (P2O5/SiO2): A Useful Heterogeneous Alternative for the Ritter Reaction. -A broad spectrum of alcohol substrates can be converted to amides in a highly efficient manner under conditions A). A chemoselective transformation is achieved with nitriles (Ia) and (Ie) in the presence of benzyl alcohol. -(TAMADDON*, F.; KHOOBI, M.; KESHAVARZ, E.; Tetrahedron Lett. 48 (2007) 21, 3643-3646; Dep. Chem., Coll. Sci., Yazd Univ., Yazd 89195, Iran; Eng.) -Mais 35-057

Sulfated polyborate: A mild, efficient catalyst for synthesis of N-tert-butyl/N-trityl protected amides via Ritter reaction

“…4 Till date, various alternative methodologies have been reported to achieve chemo-selectivity with higher yields under milder conditions to improve Ritter reaction. These include a variety of Lewis and Bronsted acid/reagents such as sulfuric acid, 5,6 Mg(HSO 4 ) 2 , 7 silica-supported Fe(ClO 4 ) 3, 8 trifluoromethane sulfonic acid, 9 trifluoromethane sulfonic anhydride, 10 zeolites, 11 (BF 3 •OEt 2 ), 12 MnO 2 •SiO 2 , 13 bismuth Triflate, 14 DNBSA, 15 Ca(HSO 4 ) 2 , 16 TiCl 4 , 17 P 2 O 5 •SiO 2 , 18 Fe 3+ -K10 Montmorillonite, 19 PMA•SiO 2 , 20 Nafion-H, 21 NaHSO 4 /SiO 2 , 22 and H 2 PW 12 O 40 . 23 In addition to this, various catalytic systems are also reported which include silica sulfuric acid, 24 silica supported sulfonic acid, 25 silica-bonded Npropyl sulphamic acid (SBNPSA), 26 silica boron-sulfuric acid nanoparticles (SBSANs), 27 HClO 4 -functionalized silica-coated magnetic nanoparticles, 28 sulfated tungstate, 29 * For correspondence alumina-methanesulfonic acid (AMA), 30 nanocat-Fe-OSO 3 H, 31 35 Al(HSO 4 ) 3 , 2 ionic liquids, 36 iodine, 37 and polyvinylpolypyrrolidone-supported boron trifluoride.…”

Polyoxometalate–Ionic Liquid-Catalyzed Ritter Reaction for Efficient Synthesis of Amides

“…During the past decades, enormous efforts have been made to overcome this problem, and numerous achievements in terms of developing high active catalysts that allow the reaction to perform under mild conditions have been established. Examples include solid supported-acid catalysts, [8] metal complexes, [9][10][11][12] perfluorinated sulfonic acid resin (Nafion-H), [13] and many others. [14,15] Nevertheless, some of them remain to have limitations in terms of high catalyst loading, limited substrate scope, as well as poor selectivity.…”

“…With the optimized reaction conditions in hand (Table 2, entry 3), the substrate scope of alcohols was first explored. As shown in Scheme 1, various 1-phenylethanol derivatives can be transformed into the corresponding Ritter products in up to 95% yields (2)(3)(4)(5)(6)(7)(8)(9)(10)(11). Among them, 1-phenylethanols with electron-withdrawing groups (2-8) generally gave better results than those with electron-donating groups (9)(10)(11).…”