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

Koichi Mikami, Yukihiro Motoyama, Masahiro Terada

Research output: Contribution to journalArticlepeer-review

262 Citations (Scopus)

Abstract

Asymmetric Diels-Alder (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 enrfo-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 (J?)-l with (S>1 or (±)-l.

Original languageEnglish
Pages (from-to)2812-2820
Number of pages9
JournalJournal of the American Chemical Society
Volume116
Issue number7
DOIs
Publication statusPublished - 1994 Apr 1
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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