Short Synthesis of Novel Recyclable Chiral Bifunctional Thioureas from Aminoalkyl Polystyrene and their use as Organocatalysts in Stereoselective aza‐Henry Reaction.

Abstract

Abstract.A series of supported bifunctional thioureas has been prepared, in one or two steps, from commercially available aminoalkyl polystyrene resins. They differ in the length of the tether attaching the thiourea to the polymer chain, and the nature of the amino thiourea component. All the materials are able to promote stereoselective aza-Henry reaction with very good stereoselection, and they can be recycled maintaining the catalytic activity.

Supported Bifunctional Chiral Thioureas as Catalysts in the Synthesis of 3‐Amino‐2‐Oxindoles through Enantioselective aza‐Friedel‐Crafts Reaction: Application in Continuous Flow Processes

“…Eight supported bifunctional thioureas (I-VIII) derived from cinchona alkaloids were prepared, in two steps, as previously described [19] (Scheme 1). The reaction of commercially available methyl-, ethyland n-butylamino polystyrene with thiophosgene lead to isothiocyanates 1-3 in near quantitative yield.…”

Synthesis of Enantioenriched 3‐Amino‐3‐Substituted Oxindoles by Stereoselective Mannich Reaction Catalyzed by Supported Bifunctional Thioureas.

“…For comparative purposes bifunctional thioureas I and II , squaramide III , a novel thiourea IV derived from (9 S )‐9‐deoxy‐9‐aminoquinine, and polystyrene‐supported thioureas V and VI were selected as catalysts, and their activity tested in the addition of 2,4‐pentanedione 2 a to isatin ( N ‐Boc) ketimine 1 a as a model reaction (Table ). The reactions were carried out by stirring a mixture of 0.15 mmol of 1 a and two‐fold excess of 2 a in 0.4 mL of dichloromethane (DCM) at rt, in the presence of 5 mol% of the corresponding catalyst.…”

Chiral Bifunctional Thioureas and Squaramides Grafted into Old Polymers of Intrinsic Microporosity for Novel Applications

“…5,5′,6,6′-Tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane was purchased from Alfa Aesar (Karlsruhe, Germany), and 2,3,5,6-tetrafluorophtalonitrile was from Sigma-Aldrich (Madrid, Spain. 1-((1R, 2R)-2-Aminocyclohexyl)piperidine [40], 9,10-Dimethyl-9,10-ethano-9,10-dihydro-2,3,6,7-tetrahydroxy-anthracene [41], isothiocyanates 1 and 4 [42], and chiral hemisquarate 2 [43] were prepared as described in the literature. 1,3-Dicarbonyl compounds 5a – c and trans -β-nitrostyrene 6 are commercially available, and they were used as received.…”

“…Thiourea VI was obtained (Scheme 1b) by direct condensation of amine-PIM-CO-100 (150 mg, 0.56 mmol, 1 equiv.) with 1-((1R,2R)-2-isothiocyanatocyclohexyl)piperidine 4 (251 mg, 1.12 mmol, 2 equiv) as previously described [42] to produce 211 mg of polymer (77% yield). An effective functionalization, f = 1.36 mmol g −1 , was calculated on the basis of sulfur elemental analysis (C: 61.93; H: 6.33; N: 7.40; S: 4.36).…”