Homodecoupled J-resolved HSQC: Direct determination of accurate 1H-13C RDCs in a single PMMA compressed gel sample

LAURA CASTAÑAR; MANUELA GARCÍA; ERICH HELLEMANN; PAU NOLIS; MANUELA E. GARCIA; TEODOR PARELLA

La Jolla

Conferencia; Small Molecules Are Still Hot NMR Conference; 2016

A robust J-resolved HSQC (HD-J-HSQC) experiment affording highly resolved 1JCH/1TCH splittings along the indirect dimension (F1) and homodecoupled 1H signals in the detected dimension (F2) is proposed. The experiment enables the in-situ distinction of both isotropic and anisotropic components of molecules dissolved in compressible PMMA gels, allowing a rapid and reliable determination of accurate 1DCH for CH systems and sum 1DCHa+1DCHb for diastereotopic CH2 protons from a single measurement. It will be shown that the combination of several resolution enhancement techniques introduces substantial improvements in spectral quality, sensitivity and both signal and digital resolution. This is a good example showing that RDCs of variable size and sign can be accurately determined from a single NMR spectrum, minimizing typical errors of measuring them from two different sample conditions. Experimental data will be used to evaluate the structural diastereoisomeric discrimination in two natural products: strychnine and ludartin.