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Author(s): Jürgen Soutschek (corresponding author) [1]; Akin Akinc [2]; Birgit Bramlage [1]; Klaus Charisse [2]; Rainer Constien [1]; Mary Donoghue [2]; Sayda Elbashir [2]; Anke Geick [1]; Philipp Hadwiger [1]; [...]

Organocatalytic Friedel‐Crafts aminoalkylation reaction is demonstrated in this study for the construction of biologically important hybrid molecular architectures of carbazole containing 3‐amino oxindoles using bifunctional cinchonidine derived thiourea organocatalyst. The Friedel‐Crafts functionalization of 4‐hydroxy carbazole with isatin derived ketimines well performed with a wide range of substrates resulted in excellent yields (up to 95 %) and enantioselectivities (up to 99 % ee) of the desired products. A minimal catalyst loading (0.5 mol%) was utilized at ambient temperatures under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Enantioselective construction of bioinspired coumarin and oxindole hybrid structures always enduring challenges in organic chemistry due to the generation of asymmetric quaternary/spiro center at the C3 position of oxindole. Herein, we demonstrated a facile enantioselective synthesis of highly functionalized 3,3'‐disubstituted oxindole derivatives containing 3‐acetyl coumarins and pyranocoumarin fused spirooxindoles using L‐proline derived bifunctional thiourea organocatalyst through Aldol reaction and Michael addition/cyclization. The L‐proline derived thiourea catalyst well performed with broad substrate scope to produce desired products in very good yields (up to 95 %) and excellent enantioselectivities (up to 99 % ee). [ABSTRACT FROM AUTHOR]

An asymmetric [3 + 2] formal cycloaddition reaction between oxindole α‐keto esters and enals has been developed. This α,γ‐regioselective reaction afforded multifunctional carbocyclic oxindoles via dienamine‐enamine cascade reaction followed by isomerization. Furthermore, a highly enantioselective Diels‐Alder reaction was demonstrated between 2,4‐dienals and oxindole α‐keto esters via trienamine intermediates. Chiral secondary amine catalyzed the both reactions under mild conditions and the cyclized products were isolated in moderate to good yields with good diastereoselectivities (>20:1 dr) and enantioselectivities (up to 99 %). [ABSTRACT FROM AUTHOR]

The synthesis of highly functionalized spirocarbocyclic oxindoles was accomplished for the first time, using a Hauser annulation strategy. A reaction between methylene-indolinones and arylsulfonylphthalides catalyzed by cesium carbonate gave access to a new class of biologically important spiro[indoline-3,2'-naphthalene] derivatives in very good yields. [ABSTRACT FROM AUTHOR]

3-Alkynyl-3-OBoc (Boc = tert-butoxycarbonyl) oxindole derivatives underwent a CuII-mediated stereo- and regioselective Friedel-Crafts alkylation/5- exo- dig-cyclization with 2-naphthols or cyclic 1,3-diketones. This gave spirooxindole [2,1- b]furan motifs in good to excellent yields under ambient conditions, and the process has a wide substrate scope. [ABSTRACT FROM AUTHOR]

The first thiourea catalysed asymmetric [3+2] cycloaddition reaction between azomethine imines and malanonitriles was developed. Using this novel synthetic strategy, hybrid molecules containing N,N-bicyclic pyrazolidinones fused with enaminonitriles were synthesized in good yields with excellent enantioselectivities (up to 98% ee). [ABSTRACT FROM AUTHOR]

The catalytic efficiency of a bifunctional chiral thiourea derived from L-proline was evaluated in the asymmetric direct vinylogous Michael reaction of α,α-dicyanoolefins to β-nitrostyrenes with an electron- releasing or electron-withdrawing substituent in various positions. The corresponding adducts were isolated in good yields, with excellent diastereo- (>99%) and enantioselectivity (up to 95%). The Michael adducts were further functionalized to achieve the synthesis of polycyclic fused pyrrolidines with three contiguous stereocenters in good enantioselectivities. [ABSTRACT FROM AUTHOR]

A new synthetic strategy to construct spirooxindole-naphthopyran scaffold has been demonstrated via Friedel-Crafts type/hemiketalization of oxindole α-ketoester with 2-naphthol. Under the established reaction condition, quaternary chiral center at C3-position of oxindole has been created with very good asymmetric induction up to 98 % for a broad range of substrates. DFT calculations, which account for the stereochemical outcome, were performed. [ABSTRACT FROM AUTHOR]

Diverse bispiro-3,4-dihydropyrans consisting of oxindole moieties with three contiguous chiral centers and vicinal quaternary stereocenters were synthesized with very good yields of up to 92 % and excellent enantioselectivity of up to 99 % ee by using a proline-derived thiourea organocatalyst. [ABSTRACT FROM AUTHOR]

A new bifunctional squaramide organocatalyst derived from l-proline mediated the first enantioselective synthesis of dihydrospiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives in excellent enantioselectivity by reacting pyrazolones with isatylidine β,γ-unsaturated α-ketoester. This new catalyst outperformed widely used thioureas and squaramides in inducing enantioselectivity. [ABSTRACT FROM AUTHOR]

Chiral Lewis bases facilitated the synthesis of highly functionalized spirooxindoles containing α- exo-methylene-γ-butyrolactones in high yields (76-92 %) and excellent enantioselectivities (up to 98 % ee) at ambient temperature. [ABSTRACT FROM AUTHOR]

Tartrate-derived bioxazoline ligands, which form a five-membered chelate ring with metals, were evaluated for use in the asymmetric allylic alkylation (AAA) reactions of various symmetrical and unsymmetrical allyl acetates. Excellent enantioselectivities were achieved by using both symmetrical and unsymmetrical allyl acetates. [ABSTRACT FROM AUTHOR]

Derivatives of 2,3-dihydroquinazolinones (2,3-DHQZs) are prized for their prevalent pharmaceutical applications. Although there are potential applications, methods available for the enantioselective synthesis of these valuable compounds are scarce, since the chiral aminal center is prone to racemization. We have overcome the difficulties in the catalytic enantioselective synthesis of 2,3- DHQZs using Sc(III)-inda-pybox as a catalyst, in a process with a broad substrate scope [ABSTRACT FROM AUTHOR]

Novel C2-symmetric chiral bioxazolines were synthesized in good yields by the fusion of optically active acids with a tartaric acid derivative. Complexes of these products with copper(II) acetate monohydrate were found to be excellent catalysts for the Henry reaction, giving various nitro alcohols in very good yields and up to 84% enantiomeric excess. Although only five-membered chelation is possible with these ligands, they give better enantioselectivities than other bioxazoline ligands that undergo similar coordination. [ABSTRACT FROM AUTHOR]

Enantioselective synthesis of 2,3-dihydroquinazolinones (DHQZs) was accomplished using readily available Sc(III)-inda-pybox as the catalyst. This is the first report on the metal catalyzed asymmetric intramolecular amidation of imines to synthesize DHQZs. [ABSTRACT FROM AUTHOR]

Examines the reactions of catalytic B-steroselective epoxidation of ...5 unsaturated steriods with a novel ruthenium II complex under aerobic conditions. Description of the reaction conditions; Experimental procedures utilized.

The new proline-derived squaramide organocatalyst is shown to exhibit higher efficiency than known thiourea and squaramide ligands. [ABSTRACT FROM AUTHOR]