. Author manuscript; available in PMC: 2012 May 25.

Published in final edited form as: J Am Chem Soc. 2011 May 3;133(20):7916–7925. doi: 10.1021/ja201249c

Table 3. Optimal Temperatures for Stereoselective Epoxide-Opening Spirocyclization of Glycal Epoxide Substrates.^a.

graphic file with name nihms-294153-t0014.jpg

entry	substrate^a	T (°C)	CD₃OD (M)	inversion (18, 8-10)	retention (19, 11-13)	glycoside (20, 14-16)
1	17	−63	17.8^b		nr
2	17	−35	17.8	93	0	7

3	5c (R = H)	−35	17.8	>98	<2	0
4	5c (R = H)	−35	11.9^c	>98	<2	0
5	5c (R = H)	−35	0		nr

6	6c (R = H)	−20	17.8	70	30	0
7	7c (R = H)	0	17.8	0	41	59

Glycal epoxides generated in situ from glycal precursors with DMDO (−78 °C, 10 min), then warmed to the indicated temperature in the NMR probe.

6:1:1.3 CD₃OD/CDCl₃/acetone.

4:3:1.3 CD₃OD/CDCl₃/acetone.

R = CH₂CH₂OTBDPS; nr = no reaction.

Table 3. Optimal Temperatures for Stereoselective Epoxide-Opening Spirocyclization of Glycal Epoxide Substrates.a.