Carbohydrates Organotin

In general, the carbohydrate-organotin(IV) complexes have been studied by and or, especially by multinuclear NMR ( Sn, H, and... 

Lithium bis(dimethylphenylsilyl)cuprate and lithium methyl(dimethylphenyl-silyl)cuprate have been used to effect a conjugate addition of the dimethylphenyl-silyl moiety to some carbohydrate enones. Use of trimethylstannyl lithium and tributylstannyl lithium also afforded conjugate addition products. In a new approach to carbohydrate organotin compounds, tributylstannylcopper has been used as a source of nucleophilic tributyltin to effect displacements of a primary tosylate, an allylic bromide and addition to an aldehyde. ... 

This technique has been applied to the determination of arsenic, selenium, organocompounds of arsenic, mercury and tin in soils, carbohydrates, total sulphur, arsenic, antimony, bismuth, selenium and organocompounds of mercury, tin and silicon in non-saline sediments, arsenic, bismuth, selenium or organotin compounds in saline sediments and arsenic and selenium in sludges. 

Figure 12. Example of organotin-mediated mnltiple carbohydrate esterification.

It has been demonstrated that organotin-mediated multiple carbohydrate esterifications can be controlled by the acytaring reagent and the solvent polarity. When acetyl chloride is used, the reactions are under thermodynamic control, whereas when acetic anhydride is employed, kinetic control takes place. Very good selectivity can furthermore be obtained in more polar solvents. These results can be used in the efficient preparation of prototype carbohydrate structures. 

Radical chain reactions can take place via organotin reagent without hydrogen donors such as allyltin [38, 39]. This methodology has been applied to synthesize some important chiral precursors of natural products (for example pseudomonic acid). Thus, the pentose derivative 35 affords the compound 36 with retention of configuration via the carbohydrate radical R- at C-4 position [Scheme 18]. 

Chemical shifts for tin atoms in typical carbohydrate-derived organotin compounds are listed in Tables I and II. In general, the signals of U9Sn... 

Some of the most exciting developments in the applications of organotin derivatives to carbohydrate chemistry have come in their use for the synthesis of glycosides. These intermediates have served as both glycosyl donors and glycosyl acceptors. Applications in the former area are discussed first and are listed in Table X. 

Organotin ether derivatives continue to be utilized in the regioselective acylation and alkylation of carbohydrates. The 3-O-acylation of benzyl a-L-lyxopyranoside used the dibutylstannylene method while a polymer supported aryl(butyl)tin dichloride reagent has been used catalytically in the selective 6-0-... 

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