Um estudo sistemático das correlações de longo alcance em espectros de HMBC foi feito para uma série de ésteres etílicos do ácido cis-e trans-3-(4-oxo-4H-chromen-3-il) acrílico e os derivados 5-hydroxilados. Os resultados foram comparados com os já observados para espectros IMPEACH-MBC e CIGAR-HMBC. Um acoplamento incomum do tipo A systematic study about the long-range correlations observed in the HMBC spectra of a series of cis and trans 3-(4-oxo-4H-chromen-3-yl)-acrylic acid ethyl esters, and 5-hydroxy derivatives, was carried out. The results were compared with those observed in IMPEACH-MBC and CIGARHMBC spectra. An uncommon 5 J C,H between the methyl protons and the C α to the carbonyl group was observed in these systems as well as in ethyl chrotonate. The complete assignments of the 1 H and 13 C NMR spectra are provided.