Acetate → Calanolide

HRID 1387602Notes

Reaction equation

HRID 1387602 reaction equation
[CH3:1][CH2:2][CH2:3][C:4]1[C:10]2[C:11]3[O:25][C:24]([CH3:27])([CH3:26])[CH:23]=[CH:22][C:12]=3[C:13]3[O:18][C@H:17]([CH3:19])[C@@H:16]([CH3:20])[C@H:15]([OH:21])[C:14]=3[C:9]=2[O:8][C:6](=[O:7])[CH:5]=1.CCCC1C2C3OC(C)(C)C=CC=3C3O[C@@H](C)[C@H](C)[C@@H](O)C=3C=2OC(=O)C=1.C([O-])(=O)C.C(=O)([O-])N>CCCCCC.C(O)C>[CH3:1][CH2:2][CH2:3][C:4]1[C:10]2[C:11]3[O:25][C:24]([CH3:27])([CH3:26])[CH:23]=[CH:22][C:12]=3[C:13]3[O:18][CH:17]([CH3:19])[CH:16]([CH3:20])[CH:15]([OH:21])[C:14]=3[C:9]=2[O:8][C:6](=[O:7])[CH:5]=1

Participants

6

Reactant 4

HCID 175AcetateHCID 276CarbamateHCID 64972(+)-Calanolide AHCID 384854(-)-Calanolide A

Product 1

HCID 1201Calanolide

Reagents, catalysts & solvents 1

HCID 21879635Ethanol hexaneSolvent

Procedure

The synthetic (±)-1 was resolved into enantiomers, (+)-calanolide A and (−)-calanolide A, by preparative HPLC66. Thus, using a normal phase silica gel HPLC column (250 mm×4.6 mm I.D. Zorbasil, 5 μm particle size, MAC-MOD Analytical, Inc., PA, USA), the synthetic (±)-1 appeared as one peak with a retention time of 10.15 minutes when hexanelethyl acetate (70:30) was used as the mobile phase at a flow rate of 1.5 minutes and a wavelength of 290 nm was used as the uv detector setting. However, on a chiral HPLC column packed with amnylose carbamate (250 mm×4.6 mm I.D. Chiralpak AD, 10 μm particle size, Chiral Technologies, Inc., PA, USA), two peaks with retention times of 6.39 and 7.15 minutes in a ratio of 1:1 were observed at a flow rate of 1.5 mL/min. The mobile phase was hexane/ethanol (95:5) and the uv detector was set at a wavelength of 254 nm. These two components were separated using a semi-preparative chiral HPLC column, providing the pure enantiomers of calanolide A. The chemical structures of the separated enantiomers, which were assigned based on their optical rotations and compared with the reported natural product, were characterized by spectroscopic data. HPLC chromatograms of (±)-calanolide A and its optical forms are shown in FIG. 1.

Workup

  1. customThese two components were separated

Sources & evidence

ORD record
ord-432a9d3fd8fc486b87b25b3bf38a2856
Source dataset
uspto-grants-2001_07
Patent number
US06268393B1

Reaction notes

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