Organocatalytic Enantioselective Friedel-Crafts Reaction of 1-Naphthols with Isatins and an Unexpected Spontaneous Dehydration Process

Enantioselective organocatalytic Friedel-Crafts reaction of electron-rich phenols and isatins by Takemoto's thiourea catalyst

Takemoto's catalysts were used to organocatalyze the enantioselective Friedel-Crafts reaction with different electron-rich phenols and substituted isatins. The resulting 3-aryl-3-hydroxyl-2-oxindoles were obtained in good yields (85-96%) with up to 99% ee. The substrate scope was broadened with this methodology compared to reported examples catalyzed by cinchonidine thiourea.

Urea derivative organocatalyzed enantioselective Friedel-Crafts alkylation of α-naphthols with isatins

An organocatalytic enantioselective Friedel-Crafts alkylation of α-naphthols with isatin derivatives was catalyzed by Takemoto-type urea catalyst to give optical active 3-(naphthalen-2-yl)-3-hydroxy-2-oxindoles in 75%-92% yields with up to 95% enantiomeric excess (ee) value. The catalyst type and the substrate scope were broadened in this methodology.

Enantioselective construction of a congested quaternary stereogenic center in isoindolinones bearing three aryl groups via an organocatalytic formal Betti reaction

An efficient enantioselective formal Betti reaction between phenols and diaryl ketimines generated in situ from isoindolinone alcohols is described.

Organocatalytic enantioselective aza-Friedel-Crafts reaction between benzothiazolimines and 2-naphthols for the preparation of chiral 2'-aminobenzothiazolomethyl naphthols

A bifunctional cinchona squaramide catalyzed enantioselective aza-Friedel-Crafts reaction between 2-naphthols and benzothiazolimines has been developed, and a series of chiral 2'-aminobenzothiazolomethyl naphthols with potential antiproliferative and anthelmintic activities have been successfully and effectively prepared in good to excellent yields (up to 98%) with excellent enantioselectivities (up to >99% ee) even in a scale-up preparation under mild conditions.

Organocatalytic enantioselective aza-Friedel–Crafts alkylation of β-naphthols and isatin-derived ketimines via a Takemoto-type catalyst

The catalyst type and the substrate scope were broadened using this methodology.

Amine-Catalyzed Highly Regioselective and Stereoselective C(sp(2) )-C(sp(2) ) Cross-Coupling of Naphthols with trans-α,β-Unsaturated Aldehydes

A metal-free C(sp(2) )-C(sp(2) ) cross-coupling approach to highly congested (E)-α-naphtholylenals from simple naphthols and enals is described. The mild reaction conditions with pyridine hydrobromideperbromide (PHBP) as the bromination reagent in the presence of piperidine or diphenylprolinol trimethylsilyl (TMS) ether as promoters enable the process in good yields and with high chemoselectivity, regioselectivity, and stereoselectivity. The process involves an unprecedented pathway of in situ regioselective 4-bromination of 1-naphthols and the subsequent unusual aromatic nucleophilic substitution of the resulting 4-bromo-1-naphthols with the α-C(sp(2) ) of enals through a Michael-type Friedel-Crafts alkylation-dearomatization followed by a cyclopropanation ring-opening cascade process. The noteworthy features of this strategy are highlighted by the highly efficient creation of a C(sp(2) )-C(sp(2) ) bond from readily available unfunctionalized naphthols and enals catalyzed by non-metal, readily available cyclic secondary amines under mild reaction conditions.

Cinchonidine thiourea catalyzed asymmetric addition of phenols to oxindole derivatives

A highly enantioselective Friedel–Crafts reaction of phenols with isatin derivatives catalyzed by Cinchona-derived thiourea provides biologically important 3-aryl-3-hydroxy-2-oxindoles in good to excellent yield with enantioselectivity up to 92% ee.