Highly Enantioselective Friedel−Crafts Alkylations of Pyrroles and Indoles with α‘-Hydroxy Enones under Cu(II)-Simple Bis(oxazoline) Catalysis

Abstract

Remarkably high and regular enantioselectivities are obtained in Friedel-Crafts alkylation reactions involving alpha'-hydroxy enone templates and Cu(II)-bis(oxazoline) complexes as catalysts. The simple elaboration of adducts provides a route to enantioenriched aldehydes, carboxylic acids, and ketones containing the pyrrole and indole frameworks.

Gold‐Catalysed Direct Couplings of Indoles and Pyrroles with 1,3‐Dicarbonyl Compounds

“…Lewis acidic metal catalysts have been employed to a lesser extent. [17] Therefore, the development of new direct C À C coupling reactions of arenes/heteroarenes is an important topic in organometallic chemistry and catalysis. [18] In our search for new and improved catalysts for the regioselective electrophilic substitution of indoles and pyrroles we studied their gold-catalysed alkenylation with 1,3-dicarbonyl compounds (Scheme 1).…”

Transition metals in organic synthesis: Highlights for the year 2005

“…Copper catalyzed enantioselective alkylations of pyrroles and indoles using ␣ -hydroxyenones (Eq. (182)) [960]. Copper catalyzed an oxidative coupling of tetrahydroisoquinolines, N,N-dimethylbenzeneamine, or 1-phenylpyrrolidine with activated methylene compounds, nitromethane, or indoles (Eq.…”

Functionalization of Indole and Pyrrole Cores via Michael-Type Additions

“…The catalytic system showed remarkable performance at 0 or 25 • C, or even at refluxing conditions (40 • C) (Scheme 28) [100]. Enones bearing a branched β-position showed lower selectivity using catalyst 93, but high enantiomeric excesses using catalyst 94.…”

“…Regarding catalyst 93, the Michael adduct 329 was obtained from N-methylpyrrole (321) and the alkylidene malonate in moderate yield (62%) and low enantioselectivity 18% ee (Scheme 71) [100]. But, the bis(oxazoline) 93-catalyzed reaction of both pyrrole (1) and N-methylpyrrole (321) with various α -hydroxy enones 95 as Michael acceptor worked perfectly (Scheme 71) [99].…”

“…tial reduction and oxidative diol cleavage afforded the aldehydes 333-334 (Scheme 72) [100]. Enantioselective Michael additions of pyrrole and indoles organocatalyzed by chiral imidazolidinones 118 and 320 were explored with B3LYP/6-31G(d) density functional theory and the enantioselectivities observed with these two catalysts have been explained [228].…”