2‐tert‐Butylimino‐2‐diethylamino‐1,3‐dimethylperhydro‐1,3,2‐ diazaphosphorine Supported on Polystyrene (PS‐BEMP) as an Efficient Recoverable and Reusable Catalyst for the Phenolysis of Epoxides under Solvent‐Free Conditions

Abstract

2-tert-Butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine supported on polystyrene (PS-BEMP) is an efficient catalyst for the ring-opening of epoxides with phenols (1.0 equiv.). Excellent yields have been obtained and in most of the cases the final products have been isolated in pure form without any additional purification step. E-factors associated to this protocol are small and further improvements were obtained by setting a cyclic continuous-flow reactor operating under solvent-free conditions (SolFC) that allowed us to minimize waste and reduce the E-factor by 95% compared to batch conditions. In addition the representative synthesis of a 2,3-dihydrobenzo-]dioxepin-5-one has been realized. Optimization of this process was achieved by setting up an automated multi-step continuous-flow reactor based on a phenolysis process and a subsequent lactonization by thermal treatment of the reaction mixture. 3-Phen-]dioxepin-5-one was isolated in pure form and on a multi-gram scale in a very satisfactory 86% overall yield and an Efactor of 1.47.

Ring‐Opening of Epoxides in Water

“…[31] Anyway this reaction is very important because is the most direct access route for the preparation of 1,2-diols, β-alkyloxy and -aryloxy alcohols.…”

Diastereoselective Three‐Step Route to o‐(6‐Nitrocyclohex‐3‐en‐1‐yl)phenol and Tetrahydro‐6H‐benzo[c]chromen‐6‐ol Derivatives from Salicylaldehydes

“…[3,10] Recently, we have thoroughly investigated the synthesis of a variety of chromene-based compounds, [11] which are a class of valuable heterocycles endowed with potent biological activity as toxins [12] that have been employed in medicine [13] and material science. [14] Our interest in this class of compounds stems from their chemical versatility because their functionalized skeleton can be used to synthesize complex molecular structures.…”

A Magnetically Separable Catalyst for Synthesis of 1‐Phenoxy‐2‐propanol Via Atom‐economic Reaction

“…9,10 Very recently, our group has disclosed an atomeconomic reaction for highly selective 1-phenoxy-2-propanol over Al 2 O 3 /MgO. 11 Magnetic separable catalysts are widely explored for heterogeneous catalysis due to its easier separation of catalyst from the reaction mixture. 12,13 As our continuous research work for overcoming the problem concerning nano-micro size catalyst separation and reusability, here we wish to report a magnetic separable catalyst prepared by active constituent Al 2 O 3 -MgO supported on magnetic oxide Fe 3 O 4 for the synthesis of 1-PhP.…”