Sulfonated polyanthracene-catalyzed highly efficient and chemoselective thioacetalization of carbonyl compounds and transthioacetalization of acetals and acylals

Abstract

A straightforward and highly efficient procedure for the thioacetalization of a variety of aldehydes and transthioacetalization of acylals and acetals in good to excellent yields using catalytic amounts of sulfonated polyanthracene (S-PAT) is reported. The reactions were carried out in the presence of 1,2-ethanedithiol and 1,3-propanedithiole at room temperature under solvent-free conditions. Thioacetals were also prepared by the reaction of aromatic ketone and dithiole using S-PAT under reflux conditions in H 2 O as green solvent. R 1 R 2 R H S S n HS(CH 2 ) n SH R 1 , R 2 = H, Alkyl, Aryl n = 2,3 X = = O, OAc, -OCH 2 C(CH 3 ) 2 CH 2 O-X X Sulfonated polyanthracene

Cyanuric chloride-catalyzed thioacetalization for organocatalytic synthesis of thioacetals

“…During the past decade, a variety of different catalytic conditions and/or agents have been developed for practical thioacetalization transformation. The typical examples such as hafnium triflate, 5 HCl, 6 BF 3 ·Et 2 O, 7 AlCl 3 , 8 InCl 3 , 9 acidic ionic liquid, 10 trichloroisocyanuric acid, 11 silica supported sulfonic acid, 12 1,3-dibromo-5,5-dimethylhydantoin (DBH), 13 functionalized sulfonic acid, 14 sulfonated polyanthracene, 15 graphene oxide 16 and glycerol, 17 to name but a few, have contributed significantly to the preparation of thioacetals. On the other hand, despite the benefits provided by these known protocols, one or more of the limits such as the dependence on metal catalyst, harsh reaction conditions or unsatisfactory substrate tolerance have been suffered.…”