Efficient Lewis Acid Catalyzed Intramolecular Cannizzaro Reaction

Asymmetric intramolecular Cannizzaro reaction of anhydrous phenylglyoxal

“…As expected, the reaction proceeded more smoothly to give (S)-isopropyl mandelate 2a in 89% yield. However, the enantioselectivity was quite low (23% ee), as in Morken's report [2]. Although (R,R)-3aÁCu(SbF 6 ) 2 was also examined, the reaction did not proceed due to the decomposition of (R,R)-PhBox ligand (entry 2).…”

“…Based on Morken's paper [2], we examined the intramolecular Cannizzaro reaction of anhydrous phenylglyoxal 1 with just two equivalents of isopropanol in the presence of 10 mol% of (R,R)-3aÁCu(OTf) 2 in 1,2-dichloroethane at room temperature (entry 1, Table 1). As expected, the reaction proceeded more smoothly to give (S)-isopropyl mandelate 2a in 89% yield.…”

“…Earlier, Morken et al reported the catalytic enantioselective Cannizzaro reaction of arylglyoxal hydrates in a 2:1 mixed solvent of 2-propanol-1,2-dichloroethane [2]. For instance, in the presence of 10 mol% each of (S,S)-2,2 0 -isopropylidenebis(4-phenyl-2-oxazoline) [(S,S)-PhBox (3a)] and Cu(OTf) 2 , 1ÁH 2 O is converted to (R)-isopropyl mandelate (2a) in 57% yield with 28% ee (Scheme 2).…”

o‐Amine‐Assisted Cannizzaro Reaction of Glyoxal with New 2,6‐Diaminoanilines

“…[10][11][12] Several studies on intramolecular Cannizzaro reactions have been reported, such as reac- tions of glyoxal derivatives with alkoxy [10] and amide anions [11] under basic conditions, and alcohol in the presence of Lewis acids. [12] The products, α-hydroxy amide derivatives, are commonly known as the significant core structure for anticonvulsion drugs [13] and fundamental components included in other pharmaceutical compounds [14] and agrochemicals, [15] and also significant synthetic precursors of biologically active substances. [16] Thus, several synthetic routes to α-hydroxy amides have been developed.…”

New Colours for Carotenoids – Synthesis of Pyran Polyenes

“…Nevertheless, some similarities with reported metal-catalyzed aldehyde reactions might be considered. [31][32][33][34] AlCl 3 clearly assists the reaction, C-C bond formation and hydride transfer, to intermediate II. Subsequent elimination of H 2 O leads to the transient allene III, which immediately rearranges to vinylogue α-pyranone 2.…”