A Cu-BOX catalysed enantioselective Mukaiyama-aldol reaction with difluorinated silyl enol ethers and acylpyridine N-oxides

Abstract

Chiral difluorinated tertiary alcohols are obtained in moderate to excellent yields and high enantioselectivities upon a Cu(ii)-catalysed reaction of difluorinated silyl enol ethers and acylpyridine N-oxides.

Enantioselective Aldol Reaction with Difluoroenoxysilanes Catalyzed by Cationic Palladium Aqua Complexes

“…Our own contribution to these “non‐difluoroenoxysilane” approaches relied on one‐pot strategies from CF 3 TMS and acylsilanes or on the use of α,α‐difluoro‐α‐trimethylsilylacetamides [13] . Some catalytic enantioselective additions of difluoroenolate precursors to various carbonyl‐type electrophiles have been reported, [10a,d–e,h,11b,12a] but examples of classical aldol reaction on standard aldehydes remain scarce (scheme 1). [11e,14] We wish to report herein a novel catalytic enantioselective addition of difluoroenoxysilanes onto aromatic aldehydes, using cationic palladium aqua complexes.…”

Titanium-catalyzed highly stereoselective anti-Markovnikov intermolecular hydroalkoxylation of alkynes to prepare Z-enol ethers

“…Meanwhile, they also serve as versatile building blocks widely used to produce various heterocycles, 2 bioactive molecules, 3 and natural products. 4 Their multiple uses make them essential intermediates in the synthesis of pharmaceuticals, pesticides, 5 aldehydes, ketones, 6 or cross-coupling reagents. 7 In view of their widespread applications, extensive attention has been paid to highly efficient synthesis of enol ethers, including base-promoted hydroalkoxylation of alkynes, 8 transition metal-catalyzed cross-coupling reactions, 9 Tebbe olefination, 10 and other types of conversions.…”

B(C6F5)3/Chiral Phosphoric Acid Promoted Asymmetric C-3 gem-Difluoroalkylation of Quinoxalin-2-ones with Difluoroenoxysilanes

“…However, development of new synthetic methodologies for the efficient synthesis of compounds with a gem -difluoroalkyl group is still desirable. Recently, difluoroenoxysilanes have emerged as excellent building blocks for the introduction of gem -difluoroalkyl groups, which can be easily prepared by defluorination of trifluoromethyl ketones in the presence of TMSCl …”