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. Author manuscript; available in PMC: 2013 Jul 11.
Published in final edited form as: Chem Rev. 2012 Apr 20;112(7):4246–4282. doi: 10.1021/cr200133c

Table 2.

1H NMR characterization of oxazaborolidine borenium equilibria

graphic file with name nihms372315u2.jpg
entry Structure B-coord R Z X Ha Hb Hc Ref
1 37 3 o-Tol Lp -- 4.54 3.40 3.24 31
2 154 3 Me Lp -- 4.35 3.40 3.05 31
3 155 3 o-Tol H NTf2 5.44 NA NA 72
4 157 3 Me H OTf 4.85 3.40 3.20 31
5 161 3 o-Tol Me NTf2 4.95 NA NA 74
6 163 3 o-Tol Br3Al− -- 5.26 3.95 3.51 75
7 156 4 o-Tol H NTf2 5.01,4.90b NA NA 72
8 158 4 Me H OTf 4.75 3.15 3.00 31
9 160 4 o-Tol Me H 4.38 3.46 3.02 74
10 157·DMF 4 Me H DMF+ 5.00 3.50 3.00 31
a

1H NMR data in ppm, CD2Cl2

b

Ha values assigned to two diastereomers