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. Author manuscript; available in PMC: 2010 Jul 9.
Published in final edited form as: Synthesis (Stuttg). 2008 Oct 1;2008(19):3148–3154. doi: 10.1055/s-2008-1067259

Table 3.

The effect of reaction conditions on the stereoselectivty of SmI2-promoted pinacol cyclization of 6a. Reactions were performed with 6 eq SmI2 in THF under the conditions listed.

Entry Reaction Conditions Quench Conditions Ratio 7: 8
1 −78 °C, 10 min, then 20 °C, 5h NaHCO3 at 20 °C 1:2.5
2 −78 °C, 10 min NaHCO3 at −78 °C >20:1
3 −78 °C, 10 min H2O at −78 °C >20:1
4 −78 °C, 10 min, then 20 °C, 10 min O2 (air) 1:1
5 −78 °C, 10 min NaHCO3 at −78 °C, then O2 (air) at −78 °C >20:1
6 −78 °C, 10 min O2 (air) at −78 °C 6a recov.
7 −78 °C, 10 min I2 at −78 °C 6a recov.
8 −78 °C, 10 min, then 20 °C, 10 min, then −78 °C, 10 min NaHCO3 at −78 °C 1:1
9 −78 °C, 10 min 1M NH4OH at −78 °C >20:1
10 −78 °C, 10 min 2M HCl at −78 °C >20:1
11 −72 °C, 10 min NaHCO3 at −72 °C >20:1
12 −61 °C, 30 min NaHCO3 at −72 °C >20:1
13 −50 °C, 10 min NaHCO3 at −50 °C >20:1
14 −25 °C, 10 min NaHCO3 at −25 °C 1:1.5
15 −78 °C, 10 min Bu3SnH, then NaHCO3 at −78 °C >20:1
16 −78 °C, 10 min CuBr, then NaHCO3 at −78 °C >20:1
17 −78 °C, 10 min MeOH, then NaHCO3 at −78 °C >20:1
18 −78 °C, 10 min PhCO2H, then NaHCO3 at −78 °C >20:1
19 −78 °C, 10 min CF3CO2H, then NaHCO3 at −78 °C >20:1
20 −78 °C, 10 min Bu3SnH, then O2 (air) at−78 °C 6a recov.
21 −78 °C, 10 min PhSH, then O2 (air) at−78 °C 6a recov.