Studies of alkoxy- and hydroxy-C-stannylated derivatives
New organotin compounds containing hydroxy- and alkoxy-functionality have been prepared. Synthesis of these organotin compounds has focused on the use of carbohydrate derivatives, from which both protected and unprotected carbohydrate organotin derivatives have been prepared. The methods of synthesis have involved the use of organotin hydrides (Ph3SnH and PhMe2SnH) and their addition to an allyl sugar and on the nucleophilic substitution of -halomethyltin compounds [Ph_4-n-mMe_mSn(CH_2I)_n]. The structures of products have been investigated in the solid state by. 13C and. 119Sn NMR spectroscopy and by single crystal X-ray diffraction, from which the atomic arrangements and packing of molecules in the crystal lattice have been determined for (3-hydroxypropyl)diphenyltin iodide, 1,6-diiodo-1,6-diphenyl-2,7-dioxa-1,6-distannacyclodecane, methyl 1,3- O -isopropylidene-5- O -[triphenyl-stannyl]-methyl--D-ribofuranoside and bis[6- O -(1,2:3,4-di- O -isopropylidine--D-galacto-pyranosyl)methyl]phenyltin iodide. Further investigations of the structures have been made by multinuclear solution NMR. Diastereotopic groups have been observed in mixed organotin compounds [Ph_3Sn(CH_2)_3OR, PhMe_2Sn(CH_2)_3OR, Ph_2MeSnCH_2OR, PhMe_2SnCH_2OR and PhMeSn(CH_2OR)_2]. Selective phenyl-tin bond cleavage was effected using iodine to give rise to mono- and diiodotin compounds. The organotin halides have been observed to undergo a rapid halide exchange process and consequently chiral tin compounds prepared by de-phenylation of Ph_2MeSnCH_2OR [R&'61 a sugar substituent] are configurationally unstable. (3-Hydroxypropyl)diphenyltin iodide was determined to be thermally unstable, protode-phenylation occurring as the result of the hydroxyl group acting as a Bronsted acid. Thermal instability of Ph_3-n-mMe_m(I)Sn(CH_2OR)_n has been observed but the underlying processes are unclear. A similar instability of the parent compounds was observed, however evidence is presented for an oxidative process involving oxidation of the -CH2Sn group.