Chiral Bis(imidazolinyl)phenyl NCN Pincer Rhodium(III) Catalysts for Enantioselective Allylation of Aldehydes and Carbonyl–Ene Reaction of Trifluoropyruvates

Abstract

Chiral NCN pincer rhodium(III) complexes with bis(imidazolinyl)phenyl ligands were found to be effective catalysts for the allylation of a variety of electronically and structurally diverse aldehydes with allyltributyltin, giving the corresponding optically active homoallylic alcohols in high yields with enantioselectivities of up to 97% ee. These complexes were also applied in the carbonyl-ene reaction of ethyl or methyl trifluoropyruvate with various 2-arylpropenes. With the aid of silver trifluoromethanesulfonate, the pincer rhodium(III) catalysts could catalyze the reaction to provide the corresponding chiral α-hydroxy-α-trifluoromethyl esters in good yields with high stereoselectivities (up to 95% ee).

Enantioselective Total Syntheses of FR901464 and Spliceostatin A and Evaluation of Splicing Activity of Key Derivatives

“…Our initial attempt at constructing pyranone 7 , according to the scheme described above, commenced with preparation of the known chiral alcohol 8 , 15 as shown in Scheme 2. Treatment of 5-methylfurfural 12 with allylmagnesium bromide, followed by lipase resolution of the resulting racemic, homoallylic alcohol 13 , provided optically active 8 in 98% ee (determined by HPLC analysis using a chiral column) and 47% yield.…”

The Future of Catalysis by Chiral Lewis Acids

“…A broad spectrum of chiral Lewis acid catalysts has been used for the carbonylene reaction, and recent examples show the adaptability of this transformation to recycling (Scheme 29) in an ionic liquid [132], to very low catalyst loadings (Scheme 30) in magnetic nanoreactors [133], as well as to the uses of unconventional asymmetric catalysts that include those of palladium(II) with C 2 -bridged chiral diphosphine ligands [134], NCN pincer rhodium(III) catalysts [135], and chiral cationic dirhodium(II,III) [136]. An intramolecular carbonyl-ene reaction has also been shown to produce polycyclic products in high yield and stereocontrol Scheme 27 Intermolecular [2+2] reaction of N-allenyl sulfonamides with vinyl arenes [125] The Future of Catalysis by Chiral Lewis Acids that were previously formed by cationic polyene cyclization (Scheme 31), thus opening a new synthetic methodology for the stereoselective synthesis of polycyclic compounds [137].…”

Enantioselective Allylation of Thiophene‐2‐carbaldehyde: Formal Total Synthesis of Duloxetine

“…[8b] and a TBOx-Cr catalyst (3 mol%, 87% ee), [8c] and the addition of allyltributylstannane catalyzed by a pincer-Rh complex (5 mol%, FULL PAPERS 95% ee) [9] were reported. The Lewis and Brønsted acid-catalyzed procedures encompass the use of a chiral Bi-(R,R)-ProPhenol complex (5 mol%, 90% ee) [10] and (R)-3,3'-bis(2,4,6-triisopropylphenyl)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate [(R)-TRIP-PA] (5 mol%, 96% ee).…”