Figure 4.
31P NMR (202 MHz, D2O) of Pα in 12a. a) Artificial mixture of 12a-1/12a-2, pH 10.2. 12a-1 was added in excess, demonstrating that the 12a-2 signal is more upfield (U in Table 1), Δδ 5.4 Hz (0.027 ppm). b) Individual diastereomer 12a-1, pH 10.6. c) Individual diastereomer 12a-2, pH 10.3.