Efficient and Atom-Economic Synthesis of α-Substituted β-Chromonyl-α,β-unsaturated Carbonyls through Molecular Rearrangement
04 June 2010 (online)
A wrong NMR prediction between the ester carbonyls
of the keto ester and conjugated ester moieties in 4f led
us to a wrong stereochemical assignment (coincidentally rightly
captioned, however). Keto esters 4a-
should be read
in E-configuration in Table 1 and Schemes
2-4. The corrected Figure 1 (structure B)
and the corresponding modified paragraph (on page 404 of the original
manuscript) are given below. The authors apologize for these mistakes.
Similar NOE effects were observed in the case of keto ester 4f. While irradiation of C2-H in 4f resulted in signal enhancement of C1′-H, the latter on irradiation led to the signal enhancement for C2-H besides a weak signal enhancement for the methylene(-OCH 2Me) proton of conjugated ester (established by HMBC and HSQC NMR experiments) (Figure 1, B). Thus, E-configuration was assigned to the keto esters 4a-g.