P. Cox, S. J. Garden, R. Howie
Jun 14, 1996
Citations
0
Influential Citations
16
Citations
Journal
Journal of Organometallic Chemistry
Abstract
Abstract A family of [ 6-O-(1,2:3,4- di -O- isopropylidene-α- d -galactopyranosyl)methyl]tin species Ph n Sn(CH 2 OR) 4− n ( 1 n = 1–3 ), Ph n Me 3−n Sn(CH 2 OR ) ( 2 n = 0–3) and Bu 3 SnCH 2 OR ( 3 ) have been prepared from 1,2:3,4- di -O- isopropylidene-α- d -galactopyranose (ROH) and the iodomethylin compounds Ph n Sn(CH 2 I) 4− n ( n = 1–3), Ph n Me 3− n SnCh 2 I ( n = 1–3 and Bu 3 SnCH 2 I. The pyranose rings in these mono-, di- and trisaccharide derivatives, as well as in IPh n Sn(CH 2 OR ) 3−n ( 4 n = 0–2 ) and IPh n Me 2−n Sn(CH 2 OR ) ( 5 n = 0, 1 ), have similar twist-boat conformations in solution. The solution δ 119 Sn NMR values for the series ( 1 n = 1–4 ) and 4 n = 1–3 )do not vary linearly with n. The X-ray diffraction study of ( 4 n = 1 ) at 120 K revealed that only one of the sugar moieties acts as a C , O -bidentate ligand, via its pyranose ring oxygen. The tin centre in solid ( 4 n = 1 ) is five-coordinate and has a trigonal bipyramidal geometry: the SnO and SnI bond lengths are 2.759(5) and 2.790 A respectively, with ISnO valency angle of 173.591)°. As indicated by the solid state solution δ 119Sn values (−177.8 and −130.7 ppm respectively), the solid state structure of ( 4 n = 1 ) does not survive on dissolution. The two pyranose rings in solid ( 4 n = 1 ) have similar conformations (intermediate between screw-boat °S 5 and the twist-boat forms °T 2 with deviations in the direction of the boat-form B 2,5 ). Compound ( 1 n = 3 ) undergoes transmetallation with PhLi to give LiCH 2 OR, which was trapped as the triphenylgermanium derivative Ph 3 GeCH 2 OR.