A facile synthesis of 3-hydroxy-3-(trifluoromethyl)-1H-pyrrol-2(3H)-ones with Brønsted acid-catalyzed condensation–cyclization reactions of β-enamino esters and ethyl trifluoropyruvate

Complete Field Guide to Asymmetric BINOL-Phosphate Derived Brønsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Brønsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates

“…In 2009, Ma was able to show that β-CF 3 -ketoesters were suitable substrates for phosphoric acid activation and subsequent reaction with various indoles 60 (Figure ) . Taking 10 mol % of catalyst ( S ) -PA 25 with ethyl trifluoropyruvate 236a at room temperature for 96 h gave the corresponding Friedel–Crafts products 256 in good yields and modest enantioselectivity.…”

An overview of the applications of chiral phosphoric acid organocatalysts in enantioselective additions to CO and CN bonds

“…Yuan and co-workers described in 2014 a single example of the ( R )- BPA25 catalysed enantioselective addition of enamine 356 to ethyl trifluoropyruvate ( 355 ) affording 3-hydroxy-3-(trifluoromethyl)-pyrrol-2-one 357 in excellent yield but moderate enantioselectivity (Scheme 108). 289 The proposed mechanism consists of an initial attack of the enamine to activated ketone 355 , leading to intermediate 358 . Next, catalyst ( R )- BPA25 is released yielding species 358′ that subsequently suffers an intramolecular cyclization, to provide γ-lactam 357 .…”

An Efficient Synthesis of Acenaphtho[1,2-b]indole Derivatives via Domino Reaction

“…Enaminones are commercially available starting materials and have proven to be a useful synthons in the construction of a variety of diverse heterocycles. This synthons has been used in the construction of indole moiety via the condensation with α,β-dicarbonyl compounds under catalyst-free [ 19 , 20 ] or acidic catalyst [ 21 ] conditions.…”