Table 3. ¹H NMR and ¹³C NMR Data for Compounds S1 and S2^a.

	S1		S2
position	δC	δH	δC	δH
1	200.3
2	120.0	6.00 s	176.5
3	167.0		21.7	2.53 m
4	25.1	2.32 m	21.7	2.53 m
5	31.0	1.78 m	133.1
		2.19 m
6	72.3	4.05 m	148.3	7.33 s
7	63.3	4.07 br s	72.1	4.76 s

^a1H NMR (500 MHz) and ¹³C NMR (125 MHz) for S1; ¹H NMR (300 MHz) and ¹³C NMR (75 MHz) for S2.