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.
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%, > or = 99% ee), accompanied by the expected diol product, (-)-(aS)-7,7'-dihydroxy-8,8'-biquinolyl (1), in modest enantiomeric excess (> or =37%, > or =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).
Blakemore
Paul R
PR
Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003, USA. paul.blakemore@science.oregonstate.edu
Milicevic
Selena D
SD
Zakharov
Lev N
LN
D000818:Animals; D002073:Butanes / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D004952:Esters / Q000737:chemistry; D013058:Mass Spectrometry; D009942:Organometallic Compounds / Q000737:chemistry; D010179:Pancreas / Q000201:enzymology*; D011804:Quinolines / Q000737:chemistry / Q000378:metabolism*; D012503:Saponins / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D002787:Sterol Esterase / Q000378:metabolism*; D014631:Valerates / Q000737:chemistry / Q000378:metabolism*
C526758:2,2'-di-tert-butyl-7,7'-dihydroxy-8,8'-biquinolyl; C526728:7,7'-dihydroxy-8,8'- biquinolyl dipentanoate; D002073:Butanes; D004952:Esters; D009942:Organometallic Compounds; D011804:Quinolines; D012503:Saponins; D012997:Solvents; D014631:Valerates; C046771:butyllithium; D002787:Sterol Esterase