Crystal structure of tylophorine methiodide monohydrate,C25H30NO 4 + I−·H2O

The crystal structure of tylophorine (Chemical name 2,3,6,7 tetramethoxy phenanthro [9,10:6, 7] indolizidine. Contribution No. 0871.) methiodide monohydrate has been determined. C₂₅H₃₀NO ₄ ⁺ I^–·H₂0, triclinic, P,a=8.831(1)Å, b=10.842(2),c=13.902(2), =105.0(1)^o, =104.7(1), =97.3(1),V=1210.22ų, Z=2,D _x =1.428 g./cm^–3, (CuK)=1.54184Å, (CUK)=107.2 cm^–1, F(000)=544,T=295^oK,R=0.038,Rw=0.046, for 2331 observed reflections withI2(I). Apart from van der Waals forces, the structure is stabilized by two hydrogen bonds of the type Ow(H) ... O and Ow(H) ... I^– involving the water molecule as the donor and atom O4 of the methoxy group and I^– as acceptors.     

Total synthesis of (R)-tylophorine by using an asymmetric hydrogenation of the allyl alcohol

An efficient synthesis of naturally occurring (R)-tylophorine is described. The alkaloid was prepared in seven steps from a known phenanthryl aldehyde with an overall yield of 14.2%. Asymmetric hydrogenation of an allyl alcohol was employed as a key step for installing a stereogenic center with good enantioselectivity (77% ee), and the ee value of the ω-chloro alcohol was improved to 95% by recrystallization. After azidation and oxidation of the enantio-enriched ω-chloro alcohol to the precursor of the Schmidt reaction, the chirality transfer in the stereospecific 1,2-migration furnished the chiral carbon in the alkaloid. Finally, a one-pot deformylation/Pictet-Spengler cyclization completed the total synthesis of (R)-tylophorine.