136962-61-3Relevant academic research and scientific papers
Asymmetric catalysis of Diels-Alder cycloadditions by an MS-free binaphthol-titanium complex: Dramatic effect of MS, linear vs positive nonlinear relationship, and synthetic applications
Mikami, Koichi,Motoyama, Yukihiro,Terada, Masahiro
, p. 2812 - 2820 (1994)
Asymmetric Diets-Aider (D.-A.) reaction of 5-hydroxynaphthoquinone (juglone) with butadienyl acetate catalyzed by the binaphthol-derived chiral titanium (BINOL-Ti) complex 1 proceeds in only 9% ee in the presence of molecular sieves (MS). Remarkably, however, this reaction proceeds in 76-96% ee with BINOL-Ti complex 1 freed from MS to provide the endo-adducts useful for the synthesis of anthracyclines and tetracyclines. The solid MS-free BINOL-Ti complex 1 is stable for months at -20°C. Enhancements in endo selectivity and asymmetric induction are observed with the MS-free BINOL-Ti 1 also in the catalyzed D.-A. cycloaddition of methacrolein and glyoxylate with 1,3-dienol ethers and esters. The glyoxylate adducts can be converted to the mevinolin (compactin) intermediates. Surprisingly, the MS-free complex 1 exhibits not only a linear relationship between the ee's of BINOL-Ti 1 and the D.-A. products but also a positive nonlinear effect (asymmetric amplification), depending simply on the mixing manner of (R)-1 with (S)-1 or (±)-1.
Chiral titanium complex-catalyzed Diels-Alder reaction: A practical route to anthracycline intermediates
Mikami,Terada,Motoyama,Nakai
, p. 643 - 646 (2007/10/02)
Asymmetric Diels-Alder reactions of methacrolein and 1,4-naphthoquinone with 1,3-dienol derivatives catalyzed by the chiral binaphthol (BINOL)-derived titanium complex 1 are shown to provide the corresponding endo-adducts in high enantiomeric purity. The
