TABLE 5.
Determination of the absolute configuration and enantiomeric purity of biphenyl-, phenanthrene-, and anthracene-cis-dihydrodiols by 1H-NMR analysis of diastereomeric MPBA estersa
| Compound | Enzyme | Compound relative yield (%) | −OCH3
|
−CH3
|
||||
|---|---|---|---|---|---|---|---|---|
| Derivative type | δ (ppm) CDCl3 [C6D6] | Δδ (ppb) CDCl3 [C6D6] | δ (ppm) CDCl3 [C6D6] | δ (ppb) CDCl3 [C6D6] | cis-Dihydrodiol absolute configurationb (enantiomeric purity [%]) | |||
| (−)-cis-3,4-Dihydroxy-3,4- dihydrobiphenyl | NDO-F352V | 96% | (S)-MPBA | 3.238 [3.187] | +6 [+21] | 1.4195 [1.584] | −5 [−20] | 3S,4R (75) |
| (R)-MPBA | 3.232 [3.165] | —c | 1.4245 [1.601] | — | ||||
| (−)-cis-1,2-Dihydroxy-1,2- dihydrophenanthrene | NDO-F352V | 83% | (S)-MPBA | 3.220 | +72 | 1.368 | −74 | 1S,2R (91) |
| (R)-MPBA | 3.148 | — | 1.442 | — | ||||
| (+)-cis-3,4-Dihydroxy-3,4- dihydrophenanthrene | NDO-F352V | 17% | (S)-MPBA | 3.115 | −126 | NDc | — | 3S,4R (>95) |
| (R)-MPBA | 3.241 | — | ND | — | ||||
| (+)-cis-3,4-Dihydroxy-3,4- dihydrophenanthrene | BPDO (B8/36) | 90% | (S)-MPBA | 3.115 | −126 | 1.452 | +159 | 3S,4R (>98) |
| (R)-MPBA | 3.241 | — | 1.293 | — | ||||
| (+)-cis-1,2-Dihydroxy-1,2- dihydrophenanthrened | BPDO (B8/36) | 10% | (S)-MPBA | 3.148 | −72 | ND | — | 1R,2S (>98) |
| (R)-MPBA | 3.220 | — | ND | — | ||||
| (+)-cis-1,2-Dihydroxy-1,2- dihydroanthracene | NDO-F352V | 100% | (S)-MPBA | 3.166 | −66 | 1.442 | +64 | 1R,2S (96.5) |
| (R)-MPBA | 3.232 | — | 1.378 | — | ||||
Chemical shifts (δ) are reported for the (−)-(S)- and (+)-(R)-MPBA esters of the cis-dihydrodiols formed from biphenyl (recorded at 360 MHz) and from phenanthrene (recorded at 600 MHz). The Δδ represents the distance and direction of the (−)-(S)-MPBA ester chemical shift from the corresponding signal of the boronate ester formed with (+)-(R)-MPBA. A negative Δδ value indicates that the signal of interest is upfield from the corresponding signal of the diastereomer formed with the opposite boronic acid; a positive Δδ means that the signal of interest is downfield from the corresponding signal of the ester formed with the opposite boronic acid.
The absolute configuration predicted for the cis-3,4-dihydroxy-3,4-dihydrobiphenyl was based on the trends in directional shifts observed for a series of 2,3-dihydrodiols. The absolute configuration of the phenanthrene cis-3,4- and cis-1,2-dihydrodiols formed by NDO-F352V was determined by stereochemical correlation with standards of known absolute stereochemistry prepared by strain B8/36 biphenyl dioxygenase (BPDO).
—, not applicable; ND, not determined.
The (+) rotation was inferred from the [α]D of the (−)-phenanthrene cis-1,2-dihydrodiol produced by JM109(DE3)(pDTG141-F352V)(pDTG511).