The compounds, 3α- and 3β-triphenylstannylcholest-5-ene, 1 and 2 respectively, have been prepared stereospecifically in reactions of Ph3SnLi with cholesteryl methane- or toluene-p-sulfonates, and of Ph3SnCl with the Grignard reagent from cholesteryl chloride, respectively. Complete 1H and 13C NMR spectral assignments for 1 have been obtained using HMBC and HMQC techniques: these have been used to aid the 13C NMR spectral assignments for 2 and 3α- and 3β-(InPh3-nSn)cholest-5-enes (n = 1-2) (9-12). Crystal structure determinations of 3α-(IPh2Sn)cholest-5-ene 9 and 3α-(I2PhSn)cholest-5-ene 10 indicate distorted tetrahedral geometries about the tin centres in both compounds. The Sn-I bond lengths are 2.731(5) Ȧ in 9 and between 2.6979(12) and 2.7173(12) Ȧ in 10. Despite the similarity in the values (ca. 60°) of the dihedral angles, Sn-C(3)-C(2)-C(1) [C(1) aliphatic carbon] and Sn-C(3)-C(4)-C(5) [C(5) olefinic carbon], the values of 3J[119Sn-13C(1)] are about twice the 3J[119Sn-13C(5)] values in each of 1, 9 and 10; in contrast, 3J[119Sn-13C(1)] and 3J[119Sn-13C(5)] values are essentially the same in each of 2, 11 and 12 [Sn-C(3)-C(2)-C(1) and Sn-C(3)-C(4)-C(5) ca. 180°].
|Number of pages||8|
|Journal||Journal of the Chemical Society - Perkin Transactions 1|
|Publication status||Published - 21 Dec 1997|