Structure of isosophoridine

On the molecular and electronic structure of matrine-type alkaloids

“….1(5), 238.0 (6), 237.8(7), and 236.4 kcal mol À1 (8) -are similar to those of a variety of proton sponges described in the literature…”

“…For compounds 1-6, the theoretical predictions can be compared with the experimental results. Thus, it is very satisfying to remark the good agreement between the DFT geometries and corresponding X-ray structures [25][26][27][28][29][30].…”

“…[2][3][4][5]. In particular, there are a number of feasible conformations for the still-elusive stereoisomers 7 and 8 [7]. For 7, theory predicts a strong (7.8 kcal mol À1 ) preference for the global minimum over the second lowest-energy conformation (A(chair)/B(twist-boat)/C(twist-boat)/D(half-chair) A/B-cisoid, A/C-trans, B/C-transoid).…”

“…In the strict sense, due to the planar configuration of the amidic nitrogen atom, the C/D ring junction should best be referred to as quasi-trans or quasi-cis. Of these compounds, only one member of the cis series has been reported thus far in the literature [7]. On the other hand, all but two of the members of the trans series have been isolated from Sophora medicinal plants and a large number of their derivatives and related unsaturated alkaloids are also known [1,2].…”

Stereochemical analysis and complete 1H/13C NMR chemical shift assignments of matrine. Application of NOE and two‐dimensional NMR techniques

“…d,l-Matrine was first synthesized by Mandell et al in 1965, albeit in low yield. 2 Later an x-ray crystallographic study of the natural product was reported which showed the relative stereochemistry of l. 3 However, very little has been published with regard to the spectroscopic characterization of matrine. In connection with a recent stereoselective synthesis of matrine by Chen et a1.…”