Multicomponent reactions in chiral ionic liquids: A stereocontrolled route to mercaptopyranothiazoles

Abstract

S O Ph Me O Ar 1 CHO N S S O Ar O O HS Ar 1 S N S Ar r.t., 76-90% Pro 2 SO 4 88-95% eeA low hazardous, one-pot, expeditious annulation involving tandem Knoevenagel, Michael and ring transformation reactions of 3-arylrhodanines, aromatic aldehydes and a mercaptoacetyl transfer agent, 2methyl-2-phenyl-1,3-oxathiolan-5-one, diastereoselectively yields 6-mercaptopyranothiazoles. The annulation is performed using a chiral ionic liquid (Pro 2 SO 4 ) as the reaction medium and catalyst, and proceeds via an isolable intermediate.

Asymmetric Michael Addition Mediated by Chiral Ionic Liquids

“…Yadav’s group has reported stereocontrolled multicomponent reactions using a chiral ionic liquid, L-prolinium sulfate 50 [ 52 ], as both solvent and catalyst to obtain mercaptopyranothiazoles [ 53 ] (Scheme 24 ). In the postulated reaction mechanism, the products are obtained by the Michael addition to arylidenes, which are generated as intermediates.…”

Multicomponent Reactions in Ionic Liquids

“…[170] The reactions were conducted at room temperature 25-30 h, followed by isolation to yield a single diastereomer in 76-90% yields. …”

Salts containing different amino acids: four types of salts with the sulfate anion

“…[15] described bis-β-alaninium sulfate (β-AlaH) 2 SO 4 and determined its structure in the centrosymmetric monoclinic space group P2 1 /c. Although there is information about the production of the lproline sulfate reagent (1:1) [16] as well as on the use of "Pro 2 SO 4 " as an ionic liquid [17], we did not nd information regarding their crystal structures. The existence of double salts with the sulfate anion containing an amino acid are worth mentioning, too; these are NH 4 (GlyH)SO 4 , K(GlyH)SO 4 [18,19,20] and NH 4 (BetH)SO 4 [21].…”