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. Author manuscript; available in PMC: 2012 Jan 1.
Published in final edited form as: Chem Sci. 2011 Jan 1;2(11):2115–2119. doi: 10.1039/C1SC00357G

Table 1.

Effect of Brønsted acids on the reductive cyclization of 6a

graphic file with name nihms337988t1.jpg
entry conditions yieldb
1 5 mol% Ru(bpy)3Cl2, no acid, 4 equiv i-Pr2NEt <5%
2 5 mol% Ru(bpy)3Cl2, 2 eq H2SO4, 4 eq i-Pr2NEt <5%
3 5 mol% Ru(bpy)3Cl2, 2 eq TFA, 4 eq i-Pr2NEt 13%
4 5 mol% Ru(bpy)3Cl2, 2 eq HCO2H, 4 eq i-Pr2NEt 58%
5 5 mol% Ru(bpy)3Cl2, 2 eq BzOH, 4 eq i-Pr2NEt 43%
6 5 mol% Ru(bpy)3Cl2, 2 eq AcOH, 4 eq i-Pr2NEt 36%
7 5 mol% Ru(bpy)3Cl2, 5 eq HCO2H, 10 eq i-Pr2NEt 66%
8 2.5 mol% Ru(bpy)3Cl2, 5 eq HCO2H, 10 eq i-Pr2NEt 95%c
9 2.5 mol% DCA, 5 eq HCO2H, 10 eq i-Pr2NEt <5%
10d 20 mol% DCA, 60 mol% Ph3P <5%
a

Reactions were irradiated using a 23 W compact fluorescent bulb.

b

Yields were determined by 1H NMR analysis against an internal standard unless otherwise noted.

c

Isolated yield.

d

Other than the light source and reaction time, this entry uses the optimized conditions from ref 11b. See Supporting Information for experimental details.