BINOL-Al catalyzed kinetic resolution of citronellal analogues: synthesis of a variety of fragrances

Enantio- and Diastereoselective Carbonyl-Ene Cyclization–Acetalization Tandem Reaction Catalyzed by Tris(pentafluorophenyl)borane-Assisted Chiral Phosphoric Acids

“…In particular, two adjacent carbon atoms can be stereocontrolled by chiral catalysts in the carbon–carbon bond-forming reaction (Scheme ). Since Yamamoto and co-workers developed the catalytic enantioselective carbonyl-ene cyclization of 3-methylcitronellal 1a with the use of a stoichiometric amount of a chiral 1,1′-bi-2-naphthol (BINOL)-Zn­(II) catalyst for the first time in 1985, , a few research groups have reported the still-challenging reaction with the use of a catalytic amount of chiral catalysts. − In particular, chiral Lewis acid catalysts, such as BINOL-Ti­(IV) catalysts by Mikami and Nakai and co-workers, Schiff base-Cr­(III) catalysts by Jacobsen and co-workers, , bis­(oxazolinyl)­pyridine (PyBOX)-Sc­(III) catalysts by Loh and co-workers, and BINOL-Al­(III) by Mino and co-workers, , have been regarded. In contrast, List and co-workers recently developed the first organocatalytic enantioselective carbonyl-ene cyclization with the use of confined chiral Brønsted acid catalysts based on a BINOL-derived imidodiphosphate.…”