The Spirobenzylisoquinoline Alkaloids

1H and 13C NMR signal assignment of benzylisoquinoline alkaloids from Fumaria officinalis L. (Papaveraceae)

“…All 1 H and 13 C NMR signal assignments for 1-10 were obtained from H,H or C,H correlations based on 2D NMR data (DQF-COSY, HMQC, HMBC). The actual shift values were taken either from the respective 1D spectra or, if spectral overlap in the 1 H NMR spectrum or poor signalto-noise ratio in the 13 C NMR spectrum did not allow the resonance frequency to be assigned unambiguously, from the corresponding HMQC or HMBC spectra.…”

“…The actual shift values were taken either from the respective 1D spectra or, if spectral overlap in the 1 H NMR spectrum or poor signalto-noise ratio in the 13 C NMR spectrum did not allow the resonance frequency to be assigned unambiguously, from the corresponding HMQC or HMBC spectra. All assignments were in good agreement with the available literature data.…”

“…All derivatives bear only one oxygen substituent in the cyclopentyl ring moiety and the absolute configuration of the whole compound class is claimed to be identical. 13 Furthermore, the occurrence of this type of alkaloid is limited to the Fumariaceae, although an exemption has been published recently.…”

“…Proton NMR parameters were as follows: /2 pulse, 9.0 µs; spectral width, 6 kHz; data points, 16K; acquisition time, 1.36 s; digital resolution, 0.72 Hz; relaxation delay, 1 s; 16 transients accumulated; zero-filled to 32K; exponential weighting function (LB D 0.1). 13 1 H /2 pulse, 9.0 µs; 13 C /2 pulse, 11.6 µs; proton domain (F 2 ) spectral width, 2.5 kHz; data points, 2K; acquisition time, 0.41 s; digital resolution, 2.44 Hz; relaxation delay, 1.9 s; four transients per increment; 13 C decoupling during the acquisition by GARP; 13 C domain (F 1 ) spectral width, 12.5 kHz; 128 increments; resolution, 97 Hz per data point; zero-filled to 512 data points; /2 shifted sine-bell squared (QSINE, SSB D 2) weighting function in both dimensions. Typical gradient-selected 1 …”

Enzyme catalysed Pictet-Spengler formation of chiral 1,1’-disubstituted- and spiro-tetrahydroisoquinolines

“…the schelhammerans or homoerythrinane alkaloids (Fig. 1a)3738. Although the biosyntheses of these compounds have not been fully elucidated, it is known that these structures are not formed directly via a PSR3940.…”