[CH3:1][C:2]1([CH3:12])[C:5](=[C:6]([CH3:8])[CH3:7])[CH2:4][C@H:3]1[C:9](O)=[O:10].[H-].[H-].[H-].[H-].[Li+].[Al+3].CO>CCOCC>[CH3:1][C:2]1([CH3:12])[C:5](=[C:6]([CH3:7])[CH3:8])[CH2:4][C@H:3]1[CH2:9][OH:10]With methylethylidene compound 5 in hand the remaining steps were as follows: The resulting acid 5a was treated with LiAlH4 in ether to furnish the (R)-(−)-maconelliol 6a {[α]24D−31.0 (c 0.1, MeOH)} in good yield, and its enantiomeric purity was determined to be 78% ee. Similarly, (1S)-(−)-verbenone (80% ee, commercially available) was also converted into (S)-(+)-maconelliol 6b {70% ee, [α]24D+22.0 (c 0.1, MeOH)}. The various spectral and GC data of synthetic (R)-(−)-6a were in good agreement with those of the natural product (Zhang, A., et al., Proc. Natl. Acad. Sci. U.S.A., 101: 9601-9606 (2004)). Thus, we were able to determine the absolute configuration of the naturally occurring maconelliol 6 to be R.
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