Fast, Efficient and Regioselective Conversion of Epoxides to β-Hydroxy Thiocyanates with NH₄SCN/Zeolite Molecular Sieve 4 Å under Solvent-Free Conditions

Abstract

Solvent-free conversion of various epoxides to their corresponding β-hydroxy thiocyanates was carried out successfully with NH4SCN/zeolite molecular sieve 4 Å system at room temperature. The reactions were completed within 2 -7 min to give thiocyanohydrins with perfect regioselectivity and isolated yields. Moreover, the zeolite can be reused for several times without losing its activity.

1,1'-Bis-Methyl-3, 3-Methylenebisimidazolium Dichloride as an Efficient Phase Transfer Catalyst for Ring Opening of Epoxides Using SCN- and N3- in water

“…18,19 Unfortunately, some of the synthetic methods available for the synthesis of azidohydrins or thiocyanohydrins suffer from disadvantages such as long reaction times, use of volatile organic solvents and expensive reagents, low regioselectivity and high temperature reaction conditions. 14,20,21 * Correspondent. E-mail: sayyahi.soheil@gmail.com As a starting point, the ionic liquid 1,1′-bis-methyl-3,3methylene-bisimidazolium dichloride was synthesised by microwave irradiation of 1-methylimidazole and dry dichloromethane under reflux condition for 15 min (Scheme 1).…”

The Application of 4Å Molecular Sieves in Organic Chemical Syntheses: An Overview

“…They disclosed the solventfree conversion of different epoxides 50 into their corresponding -hydroxy thiocyanates with NH 4 SCN/MS 4A system at room temperature. 41 The reactions gave the corresponding thiocyanohydrins with perfect regioselectivity and isolated yields (75-98%) within 2-7 minutes. The for-mation of thiirane as a side-product was not observed in the reactions.…”

Anhydrous ZnCl2: A Highly Efficient Reagent for Facile and Regioselective Conversion of Epoxides to β-Chlorohydrins

“…Herein, in line of the outlined strategies and our ongoing attention to the nucleophilic ring opening of epoxides, [39][40][41][42][43][44][45] we wish to report the facile and regioselective synthesis of β-chlorohydrins from epoxides using anhydrous ZnCl2 as an efficient promoter and source of active chloride nucleophile (Scheme 1). …”