Polymer-Supported Organotin Hydrides

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). 

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. 

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. 

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... 

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

The search for other reactions in which a polymer-supported organotin hydride is capable of substituting BusSnH as radical source has led to the application of P—CH2CH2—SnBu2H for the ring enlargement of dichloromethylcyclohexadienones. Two out of twelve examples for the preparation of tropone ring systems are shown in... 

---