Organotin polymer-supported

U. Gerigk, M. Gerlach, W. P. Neumann, R. Vieler, and V. Weintritt, Polymer-supported organotin hydrides as immobilized reagents for free-radical synthesis. Synthesis, p. 448 (1990). 

M. Gerlach, F. Jordens, H. Kuhn, W. P. Neumann, and M. Peterseim, A polymer-supported organotin hydride and its multipurpose application in radical organic synthesis, J. Org. Chem. 56 5971 (1991). 

Radical cyclization y-butyrolactones.1 On treatment of the bromoacetals 1 with Bu,SnH (AIBN), the 2-alkoxytetrahydrofuranes (2) are formed in modest yield. The yields can be increased to 85-95% by use of a polymer-supported organotin.3 The... 

Another application of the direct alkylation of metal-14 anions is the synthesis of polymer-supported organotin hydrides. These were prepared by the reaction of stannyl group was separated from the phenyl ring of polystyrene by two, three or even four carbon spacers. These polymers were found to contain 0.8-1.4 mmol of Sn-H per gram. The reducing ability of the polymer-supported organotin hydrides was monitored by reactions with haloalkanes (Scheme 22)142. 

In order to facilitate the purification step, organotin precursors supported on polymers were also used for the iododestannylation reaction740-742. The reaction occurred in reasonable reaction times, which are compatible with the use of short half-life radioactive elements, thus allowing the preparation of iodolisuride 32 (a dopamine D2 receptor... 

Dumartin and associates described the preparation of in situ polymer-supported organ-otin hydrides for use as clean reducing agents (equation 15)47, while Deleuze and coworkers reported the preparation of a novel, macroporous polymer-supported organotin hydride (37), for use in catalytic free-radical reductions (equation 16)48,49. 

In this section new advances and novel synthetic methods, potential applications and structure elucidation techniques in the field of polymer-supported organotin and organogermanium compounds are presented. 

The polymer-supported organotin dihydride 70 was shown to be an efficient reducing agent for aldehydes and ketones, but substantial loss of activity was observed after regeneration. More recently, various polymer-supported butyltin reagents (71, 72) were studied as reagents for the acetylation of sucrose158. 

SCHEME 37. A monomer polymerization route to polymer-supported organotin reagents... 

In order to prepare non-styrenic polymer-supported organotin chlorides, which are expected to show physical properties such as mechanical strength, polarity and porosity different from those of polystyrene-based supports, Deleuze and coworkers copolymerised dibutyl[3-(allyloxy)propyl]tin chloride with N-phenylmaleimide (PMI) and l,l/-(methylene-4,l-phenylene)bismaleimide (MPBMI) to prepare the polymers 88a and 88b180. 

A variety of other alkyl and aryl halides were successfully dehalogenated by polymer-supported organotin hydrides even in the presence of functional groups155,157,160,168,169,181,188. Two representative examples are shown in Scheme 39. 

SCHEME 38. Test for multiple use of polymer-supported organotin hydrides... 

The same polymer-supported organotin reagent was also used in the Barton-type deoxygenation of steroid derivatives, sugar derivatives and diols160. Furthermore, the radical deamination of secondary and tertiary amines via the corresponding isocyanides was also reported160,169. 

SCHEME 40. Barton-type deoxygenation using a polymer-supported organotin hydride... 

Hunter and coworkers started from the polymer-supported organotin chloride 95, which was reacted with aryllithium compounds to give precursors for radioiodinated pharmaceuticals192,195,196,198. 

One-dimensional 119Sn NMR spectroscopy in solution was used to characterise soluble polymer-supported organotin compounds181,199. To get a more detailed understanding of the microstructure of tin-containing polymers, 1H/13C/119Sn triple resonance 3D NMR... 

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