Microwave-Enhanced Sulphated Zirconia and SZ/MCM-41 Catalyzed Regioselective Synthesis of β-Amino Alcohols Under Solvent-Free Conditions

Abstract

A solvent-free approach for the regioselective synthesis of β-amino alcohols in shorter reaction times and higher yields, compared to conventional heating is described. It involves microwave (MW) exposure of undiluted reactants in the presence of sulphated zirconia (SZ) or sulphated zirconia over MCM-41 (SZM) as catalyst. Both acid materials can be easily recovered and reused.

Sulphated Zirconia as an Eco-Friendly Catalyst in Acylal Preparation under Solvent-Free Conditions, Acylal Deprotection Assisted by Microwaves, and the Synthesis of Anhydro-Dimers of o-Hydroxybenzaldehydes

“…In a previous work we demonstrated a similar behavior in the synthesis of β-amino alcohols. [ 37 , 38 ]…”

“…The application of sulphated zirconia as a versatile catalyst in organic transformations was enhanced by the comprehensive review published by Reddy et al [ 30 ], and other research groups in subsequent papers [ 31 , 32 , 33 ]. Following our work on the application of sulphated zirconia as an eco-friendly catalyst [ 34 , 35 , 36 , 37 , 38 ], we proposed its application in protection reactions under solvent free conditions, the deprotection of the protected moieties assisted by microwaves and the synthesis of anhydro-dimers of o -hydroxy-benzaldehydes.…”

Microwave Technology—Applications in Chemical Synthesis

“…111) via the regioselective ring opening of epoxide using sulphated zirconia (SZ) or sulphated zirconia on MCM-41 (SZM) as catalyst under solvent-free MW irradiation conditions. The reaction required shorter time and afforded higher yields compared with the conventional heating; the catalyst was recovered and reused without any loss in activity (309). …”

Synthesis of Azanucleosides through Regioselective Ring-Opening of Epoxides Catalyzed by Sulphated Zirconia under Microwave and Solvent-Free Conditions

“…In this context and as part of our ongoing research program, we have been interested since eight years ago in the preparation of sulphated zirconia and its use in organic reactions. We have proved that sulphated zirconia is an excellent catalyst in such reactions as: cyclization of 1,4-dicarbonyl compounds and substituted anilines to tetrahydroindolones [5], chemoselective synthesis of acylals from aromatic aldehydes and their deprotections [6,7], synthesis of 3,4-dihydropyrimidin-2(1 H )-ones using multicomponent reactions [8], synthesis of amino alcohols by ring-opening of epoxides [9,10] and nucleophilic addition to carbonyl compounds [11]. Presently, we desire to extend this scope to the synthesis of azanucleosides which are biologically interesting molecules, because of their activity against human tumor cell lines [12,13] and for the treatment of patients with myelodysplactic syndromes [14].…”