The triplet monoclinic and co-crystallizing triclinic polymorphs of the quasi-racemates of (−)-podopetaline and (−)-ormosanine

Abstract

An extract of Podopetalum ormondii yields crystals containing two alkaloids, but repeated recrystalliz- ation fails to resolve the two components. The crystals are typically triplets consisting of a monoclinic phase m and two identical, but differently oriented, triclinic phases t l and t2. Three data sets were collected, two from a virtual twin from which most of t2 had been cut away and one from a virtually single m crystal. Both m and t data sets were centric but proved to belong to P2m and P l respectively. Both contain chirally opposite (and hence pseudo-symmetrically related) 1 : 1 ordered arrays of (-)-podopetaline and (-)-ormosanine. Many of the bond lengths of the molecules in the t phase lay outside acceptable ranges. This could be caused by the t phase contain- ing small, but significant amounts of the corre- sponding (+) isomers or other closely related alkaloid molecules of this series, m phase: C2oH35N3.C2oH33N3, total Mr=63303, P21, a= 10.418(2), b=19-634(3), c=18-685 (3) A, /3= 104.51 (2) ° , U=37000(l'l)ik 3, Z=4, Dx = 1.145gcm -3, Cu Ka, ,4=1.5418~, tz(CuKot)= 5.2cm -~, F(000)=1400, T=298K. R=0.085 for 4319 significant reflections, t phase: as for m phase except, P1, a = 10.426(8), b= 19.574(9), c= 11.202(9)A, a=122.10(6), /3=105.25(6), y= 89.50(5) ° , U= 1844(2)~ 3, Z=2, Dx = l'149gcm -3, /z(Cu Ka)=5.21 cm -m, F(000)=700. R =0.093 for 3386 significant reflections.