Nuclear magnetic resonance spectroscopy has proven to be powerful for the study of dynamic processes. A new pulse sequence, SirX, is designed to provide boundary conditions that simplify the McConnell equations. Both an initial rate approximation and a whole curve fitting to the time course of magnetization can be used to calculate the exchange rate. These methods were used to study the exchange kinetics of N,N-dimethylacetamide. As compared with the well-established exchange spectroscopy suitable to studies of slow exchange, SirX has the advantage of being less time consuming and capable of providing more reliable kinetic data. Furthermore, by setting the observation on X-nuclei with larger chemical shift dispersion as compared with an observation on ¹H resonance, SirX extends the upper limit of a reliable determination of exchange rates. Copyright © 2015 John Wiley & Sons, Ltd.

A previous study showed that together with the festuclavine synthase FgaFS, the old yellow enzyme FgaOx3 from Aspergillus fumigatus catalyzed the conversion of chanoclavine-I aldehyde to festuclavine in the biosynthesis of ergot alkaloids. In the absence of FgaFS, a mixture containing two compounds with a ratio of 7:3 was detected in the enzyme assay of FgaOx3. NMR experiments including (DQF)-COSY, HSQC, HMBC and NOESY identified their structures as E/Z isomers of N-methyl-N-[(5R,10R)-10-(2-oxo-propyl)-2,4,5,10-tetrahydrobenzo[cd]indol-5-yl]formamide and proved the migration of the formyl group at C-8 in chanoclavine I-aldehyde to N-6 in the identified products. Copyright © 2011 John Wiley & Sons, Ltd.

The conformation of [bis-(N,N′-difluoroboryl)]-3,3′-diethyl-4,4′,8,8′,9,9′,10,10′-octamethyl-2,2′-bidipyrrin (1) in solution was studied by analyzing the ¹³C¹⁹F and ¹⁹F¹⁹F through-space spin–spin couplings. The ¹H and ¹³C NMR spectra were assigned on the basis of nuclear Overhauser effect spectroscopy (NOESY), heteronuclear single-quantum correlation (HSQC), and heteronuclear multiple-bond correlation (HMBC) experiments. The ¹⁹F spectrum of 1 was compared with that of 2-ethyl-1,3,5,6,7-pentamethyl-4,4-difluoro-4-bor-3a,4a-diaza-s-indacen (2). The ¹⁹F¹⁹F through-space spinspin coupling in 1 was thus assigned and the coupling constant was obtained by simulating the coupling patterns. The obtained conformation of 1 was compared with those of the known complexes [bis-(N,N′-difluoroboryl)]-3,3′,8,8′,9,9′-hexaethyl-4,4′,10,10′-tetramethyl-6,6′-(4-methylphenyl)-2,2′-bidipyrrin (3)and [bis-(N,N′-difluoroboryl)]-9,9′-diethyl-4,4′,8,8′,10,10′-hexamethyl-3,3′-bis(methoxycarbonylethyl)-2,2′-bidipyrrin (4). The conformational dynamics of 1, 3, and 4 was surveyed by observing the temperature dependence of the through-space coupling constants between 253 and 333 K. The ¹³C¹⁹F and ¹⁹F¹⁹F through-space spin–spin couplings thus confirm similar conformations of different BisBODIPYs in solution in contrast to earlier findings in the solid state. Copyright © 2009 John Wiley & Sons, Ltd.