Chemo-enzymatic synthesis of both enantiomers of rugulactone

The synthesis of both the (R)- and (S)-enantiomers of the natural product rugulactone has been achieved. Candida rugosa lipase hydrolyzes the butyrate ester of the protected 3-hydroxy homoallylic alcohol with very high enantioselectivity (E = 244) and provides the key intermediates with high enantiomeric purity (ee 98–99%) and excellent yields.

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(R)-1-(tert-Butyldimethylsilyloxy)hex-5-en-3-yl butyrateC16H32O3Si[α]D25=-10.2 (c 1, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (3R)

(R)-1-(tert-Butyldimethylsilyloxy)hex-5-en-3-olC12H26O2Si[α]D25=+7.8 (c 1, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (3R)

(R)-Hex-5-ene-1,3-diolC6H12O2[α]D25=+9.1 (c 1, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (5R)

(R,Z)-Methyl 5-hydroxyocta-2,7-dienoateC9H14O3[α]D25=+4.5 (c 1, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (2Z,5R)

(R)-6-Allyl-5,6-dihydro-2H-pyran-2-oneC8H10O2[α]D25=-114.1 (c 1, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (6R)

(R,E)-6-(4-Oxo-6-phenylhex-2-enyl)-5,6-dihydro-2H-pyran-2-oneC17H18O3[α]D25=-46.9 (c 1, CHCl3)Source of chirality: enzymatic resolutionAbsolute configuration: (6R,8E)