Hydroxy group interactions in stannylated carbohydrates. Structures and thermal stabilities of 5-deoxy-5-C(Ph₃Sn)-1,2-O-isopropylidene-a-D-xylofuranose, 5-deoxy-5-C-(Iph₂Sn)-1,2-O-isopropylidene-a-D- and -L-xylofuranose, and 5-deoxy-5-C-(I₂PhSn)

Structures and thermal stabilities of 5-deoxy-5-C-(Ph3Sn)-1,2-O-isopropylidene-alpha-D-xylofuranose, [(D)-3], 5-deoxy-5- C-(IPh2Sn)-1,2-O-isopropylidene-alpha-D- and -L-xylofuranose, [(D)-4 and (L)-4], and 5-deoxy-5-C-(I2PhSn)-1,2-O-isopropylidene- -alpha-D- and -L-xylofuranose, [(D)-5 and (L)-5], are reported. The hydroxy groups in the stannylated xylofuranose derivatives, 3-5, exhibit roles as Lewis bases, Bronsted acids and hydrogen bonding centres. The 5-deoxy- 1,2-O-isopropylidene-alpha-D- and -L-xylofuran-5-yl ligands operate as C-5,O-4 chelating ligands (4-membered chelate rings) in 3, C-5,O-3 chelating ligands in 4 (molecule 2) and 5 (5-membered chelate rings), and a C-5,O-4,O-3 tridentate ligand in 4 (molecule 1) [both 4- and 5-membered chelate rings]. Compounds 4, in contrast to 3 and 5, undergo slow proton-dephenylation reactions in chloroform solutions at ambient temperature. All decompose on heating at 145-155 degreesC with evolution of PhH, Me2CO and H2O. The trigonal bipyramidal tin centres in (D)-5 and (L)-5 are chiral, at least in the solid state. Different modes of O-H-O bonding are found in 3, 4 (molecule 2) and 5 compared to that in 4 (molecule 1).