(2,3- O -Isopropylidene-5- O -(triphenylmethyl)-α-D-ribofuranosyl]-triphenylstannane

Abstract

The synthesis, IR, MS, solution and solid state NMR spectra and X-ray structure of (2,3-O-isopropylidene-5-O-(triphenylmethyl)-α-D-ribofuranosyl]triphenylstannane 1 (R3Sn) are reported. Compound, 1 (R3Sn) crystallizes in the orthorhombic space group C2221 (Z = 8), with a = 8.935(4), b = 17.058(7), c = 47.94(5)A. There are two short tin–oxygen separations, at 3.030(7) [involving O4, on an alpha carbon] and 3.094(7) A [involving O2, on a beta carbon]. Only the O4 atom is considered to form a weak and additional bond to tin; this results in a deviation of the geometry at tin toward trigonal bypramid from tetrahedral, with O4 and C34 in the axial sites [C34– Sn–O4=152.3(3)°]. The conformation of the ribofuranosyl ring in the solid state is E o [P, the phase angle of pseudorotation, = 268.4(9)° and τ max , the puckering amplitude, = 38.0(6)°], while the isopropylidene ring conformation is between the envelope form, E C6, and the twist form, O3 T C6 [P = 46.5(10)° and τ max = 36.9(6)°]. In solution, the ribofuranosyl ring adopts a conformation between E o and 1 T o.