Enzymatic Resolution of 7,7‘-Dihydroxy-8,8‘- biquinolyl Dipentanoate and Its Conversion to 2,2‘-Di-tert-butyl-7,7‘-dihydroxy-8,8‘-biquinolyl

Paul R. Blakemore,* Selena D. Milicevic, and Lev N. Zakharov
Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003 paul.blakemore@science.oregonstate.edu
J. Org. Chem., 2007, 72 (24), pp 9368–9371
DOI: 10.1021/jo701611u
Publication Date (Web): November 1, 2007
Copyright © 2007 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

Abstract

Abstract Image

Incubation of (±)-7,7‘-di(pentanoyloxy)-8,8‘-biquinolyl (4) with a crude cholesterol esterase preparation (from bovine pancreas) yielded highly enantioenriched unreacted dextrorotatory material, (+)-(aR)-4 (46%, ≥99% ee), accompanied by the expected diol product, (−)-(aS)-7,7‘-dihydroxy-8,8‘-biquinolyl (1), in modest enantiomeric excess (≥37%, ≥77% ee). Treatment of scalemic diesters 4 with t-BuLi, followed by saponification in the presence of air, gave 2,2‘-di-tert-butyl-7,7‘-dihydroxy-8,8‘-biquinolyl (2) in enantio enriched form. Biquinolyl 2 is less configurationally stable than 1, racemizing rapidly in CHCl3 (t1/2(rac) = 1.9 h, rt), and with a moderate rate in MeOH (t1/2(rac) = 30.5 h, rt).

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History

  • Published In Issue November 23, 2007
  • Received July 24, 2007

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