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. Author manuscript; available in PMC: 2010 Sep 1.
Published in final edited form as: Tetrahedron. 2009 Sep 1;65(33):6447–6453. doi: 10.1016/j.tet.2009.05.066

Table 3.

Lactonization conditions and results for the conversion of 27 to 28

Entry R1 R2 R3 X Conditions Product % Yield d.r.
1 Ph H H I NaHCO3, I2, CH3CN, 0 °C 28a 91 60:40
2 Me n-Bu Me I I2, CH3CN 28b 48 80:20
3 Me n-Bu Me I KI, I2, THF, NaHCO3 28b 34 80:20
4 Et n-Bu H OH H2O, t-BuOH, AD mix 28c - -
5 Et n-Bu H I NaHCO3, I2, CH3CN, 0 °C 28d 37 80:20
6 Et n-Bu H Br NBS, THF, 0 °C 28e 76 83:17
7 Et n-Bu H I NIS, THF 0 °C 28d 92 60:40
8 Et n-Bu H I Ti(Oi-Pr)4, NIS, CH2Cl2 −20 °C 28d 34 56:44
9 Et n-Bu H OH OsO4, NMO, CH2Cl2 28c 73 100:0