Synthesis of enaminones and enamino esters catalysed by ZrOCl2· 8H2O

Aluminum Phosphate Catalyzed Free Solvent Preparation of β-enamino Esters

“…The optical rotation was found to be [α] D 20 = −623, c=1.25, in Et OH matched the literature values (entry 6) [41][42].…”

Applications of Zirconium (IV) Compounds in Organic Synthesis

“…The reactions were, for the most part, carried out under solvent-free conditions at room temperature with 20 mol% of catalyst and furnished anti--acetamido ketones (194) Very recent studies demonstrated that homoallylic amines could be prepared by multicomponent one-pot reaction of aldehydes, amines and allytributylstannane in the presence of a catalytic amount of ZrOCl 2 ·8H 2 O (Scheme 84) [179]. Thus, for the reaction shown in Scheme 83, various homoallylic amines (196) were obtained with up to 83-92% yield, when 10 mol% of ZrOCl 2 ·8H 2 O was used as a catalyst in CH 3 CN. Even the acid-sensitive aldehydes, such as furan-2-carboxaldehyde, and the sterically hindered aldehydes, such as naphthalene-2-carboxaldehyde also afforded the corresponding homoallylic amines in high yields.…”

“…More recently, this reaction has been performed employing several Lewis acids or solid acids as catalyst [189][190][191][192][193][194][195]. Although the best results were obtained with indium tribromide, zirconium salts also demonstrated a considerable activity [196][197]. The reactions were performed in presence of a catalytic amount of ZrOCl 2 ·8H 2 O or ZrCl 4 under solvent-free conditions at room temperature and were applied to a wide range of amines such as aliphatic, cyclic and aromatic amines (Scheme 90).…”

Ni(OAc)2: a highly efficient catalyst for the synthesis of enaminone and enamino ester derivatives under solvent‐free conditions

“…However, the azeotropic removal of water is usually required using a Dean-Stark trap in a refluxing aromatic solvent. [12] Several improved procedures have been reported using a variety of catalysts such as trimethylsilyl trifluoromethanesulfonate (TMSTf), [13] montmorillonite K10 under microwave irradiation [14] or ultrasound, [15] I 2 , [16] BF 3 • OEt 2 , [17] Al 2 O 3 , [18] Zn(ClO 4 ) 2 • 6H 2 O, [19] Zn(OAc) 2 • 2H 2 O, [20] [21] ZrOCl 2 • 8H 2 O, [22] NaAuCl 4 , [23] Bi(OTf) 3 , [24] Sc(OTf) 3 , [25] CAN, [26] NaHSO 4 , [27] HClO 4 • SiO 2 , [28] silica gel, [29] natural clays, [30] LProline, [31] silica chloride, [32] silica-supported sulfuric acid, [33] silicasupported antimony(III) chloride, [34] phosphotungstic acid, [35] sulfated zirconia, [36] tin tetrachloride, [37] CAN, [38] K-7 PW 11 CoO 40 , [39] copper(II) nitrate trihydrate [40] and ZrCl 4 . [41] Recently, this condensation reaction has also been performed in water, [24a,42] PEG-water [43] or ionic liquid medium.…”