Calanolide → 12-Acetoxycalanolide A
Reaction equation
[CH3:1][CH2:2][CH2:3][C:4]1[C:10]2[C:11]3[O:16][C:15]([CH3:18])([CH3:17])[CH:14]=[CH:13][C:12]=3[C:19]3[O:24][C@H:23]([CH3:25])[C@@H:22]([CH3:26])[C@H:21]([O:27][C:28]([CH3:30])=[O:29])[C:20]=3[C:9]=2[O:8][C:6](=[O:7])[CH:5]=1.CCCC1C2C3OC(C)(C)C=CC=3C3OC(C)C(C)C(O)C=3C=2OC(=O)C=1>CC(O)=O>[O:8]1[C:9]2[C:10](=[CH:11][CH:12]=[CH:19][CH:20]=2)[CH2:4][CH2:5][CH:6]1[OH:7].[CH3:1][CH2:2][CH2:3][C:4]1[C:10]2[C:11]3[O:16][C:15]([CH3:17])([CH3:18])[CH:14]=[CH:13][C:12]=3[C:19]3[O:24][C@H:23]([CH3:25])[C@@H:22]([CH3:26])[C@H:21]([O:27][C:28]([CH3:30])=[O:29])[C:20]=3[C:9]=2[O:8][C:6](=[O:7])[CH:5]=1Participants
Reactant 2
Product 2
Reagents, catalysts & solvents 1
Procedure
12-Acetoxycalanolide A (2), [α]D =+20°, gave a parent ion by HREIMS at m/z 412.1825 daltons corresponding to a molecular formula of C24H28O6. Significant fragment ions were observed for M+ --CH3 (m/z 397, 41%), M+ -AcOH (m/z 352, 30%) and M+ -AcOH--CH3 (m/z 337, 100%). The presence of an acetate group was suggested by a sharp 3H singlet in the 1H NMR spectrum at δ 2.10 and 13C NMR resonances at δ 21.2 (3H) and 170.7. The remaining 1H and 13C NMR signals for compound 2 were very similar to those recorded for calanolide A (1), except that the H12 resonance in compound 2 was shifted downfield to δ 5.97. This suggested that compound 2 was the 12-acetoxy derivative of calanolide A (1). The J10-11 (6.5 Hz) and J11-12 (6.0 Hz) couplings in compound 2 supported a pseudoaxial orientation of the chromanol ring protons. The slightly diminished chromanol proton couplings in compound 2 conceivably resulted from a slight twisting of the flexible chromanol ring. Further evidence for the proposed substituent configuration was provided by difference nOe enhancements of 2% measured between H10 and H12.
Sources & evidence
- ORD record
- ord-941e6e1439d449319b974336546b457e
- Source dataset
- uspto-grants-1999_01
- Patent number
- US05859049
Reaction notes
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