Unsymmetrical covariance processing of COSY or TOCSY and HSQC NMR data to obtain the equivalent of HSQC-COSY or HSQC-TOCSY spectra

Artifacts observed in the indirect covariance NMR spectrum of HSQC-TOCSY data have recently been analyzed and a method for their elimination proposed. More recently, unsymmetrical covariance processing has been applied HSQC and HMBC spectral data to afford long-range carbon-carbon correlation information equivalent to that obtained from n, 1-, 1,n- and m,n-ADEQUATE spectra. We now wish to describe the results obtained through the application of unsymmetrical covariance processing of HSQC and COSY or TOCSY data, which affords the equivalent of HSQC-COSY and HSQC-TOCSY data in a fraction of the time required to record these spectra directly and with considerably higher sensitivity.