Table 3.
1H NMR data of the Mosher esters of 1–4a.
| MTPA Config. | Proton Chemical Shifts | Carbinol Configuration | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| H (4) | H (5) | H (7) | H (10) | H (17) | H (18) | H (20) | H (23) | H (25) | 6R | 19R | 24S | |
| 1 S-MTPA | 1.52 | 1.33 | 1.61 | 1.15 | 1.38 | 3.38 | 1.63 | 1.99 | 1.80 | |||
| 1 R-MTPA | 1.56 | 1.35 | 1.57 | 1.13 | 1.39 | 3.39 | 1.59 | 1.97 | 1.85 | |||
| ∆δH | −0.04 | −0.02 | +0.04 | +0.02 | −0.01 | −0.01 | +0.04 | +0.02 | −0.05 | |||
| H (3) b | H (5) b | H (11) | H (13) | H (16) | H (17) | H (21) | H (24) | H (35) | 4R | 12S | 23S | |
| 2 S-MTPA | 2.58 | 1.61 | 1.41 | 3.91 | 3.82 | 3.39 | 1.92 | 1.62 | 6.73 | |||
| 2 R-MTPA | 2.64 | 1.59 | 1.61 | 4.05 | 3.76 | 3.37 | 1.58 | 1.63 | 6.98 | |||
| ∆δH | −0.06 | +0.02 | −0.20 | −0.14 | +0.06 | +0.02 | +0.34 | −0.01 | −0.25 | |||
| H (4) | H (9) | H (11) | H (17) | H (18) | H (20) | H (33) | H (34) | 10R | 19S | |||
| 3 S-MTPA | 1.52 | 1.64 | 3.34 | 1.38 | 3.34 | 1.64 | 1.41 | 0.92 | ||||
| 3 R-MTPA | 1.54 | 1.58 | 3.41 | 1.94 | 3.41 | 1.58 | 1.33 | 0.89 | ||||
| ∆δH | −0.02 | +0.06 | −0.07 | −0.56 | −0.07 | +0.06 | +0.08 | +0.02 | ||||
| H (3) | H (5) | H (11) | H (13) | H (16) | H (17) | H (20) | H (22) | H (35) | 4R | 12R | 21S | |
| 4 S-MTPA | 2.59 | 1.65 | 1.63 | 3.40 | 3.72 | 3.67 | 3.85 | 1.36 | 6.72 | |||
| 4 R-MTPA | 2.64 | 1.61 | 1.48 | 3.99 | 3.82 | 3.64 | 3.93 | 1.59 | 6.97 | |||
| ∆δH | −0.05 | +0.04 | +0.23 | −0.59 | −0.1 | +0.03 | −0.08 | −0.2 | −0.25 | |||
a CDCl3, 400 MHz, ∆δH = δS-δR; b Independent experiments acquired in C6D6 were employed only to confirm the configuration at C-4 [∆δH: H-3 (−0.01), H-5(+0.17)]. [30].