Tin Hydride Substitutes in Reductive Radical Chain Reactions

Abstract

The substitution of a functional group for a hydrogen atom is a very important transformation in synthetic organic chemistry. Reactions such as deoxygenations, deselenations, deaminations, dehalogenations, and decarboxylations fall into this category. Such reactions can be conducted efficiently using free radical chemistry. These defunctionalizations can be combined with C-C-bond forming processes. Radical reactions are generally conducted under very mild conditions. Various sensitive functional groups are tolerated under free radical conditions. Tin hydrides (Bu₃SnH, Ph₃SnH, Me₃SnH) have been successfully employed in radical chemistry over the last 40 years, however there are drawbacks associated with tin-based chemistry. Organotin compounds are toxic and very often problems occur with product purification. Therefore, various attempts have been made to overcome these problems. In the present review article, we summarize the achievements on the development of tin hydride substitutes in reductive radical chain reactions.

• 1 Introduction

• 2 Catalytic Tin Hydride Reactions, Special Workup Procedures, and Modified Tin Hydrides

• 3 Silanes as Tin Hydride Substitutes

• 4 Germanes as Tin Hydride Substitutes

• 5 C-H-Reagents in Radical Chain Reactions

• 6 Thiols in Reductive Chain Reactions

• 6.1 Polarity Reversal Catalysis

• 6.2 Some other Chain Reactions Mediated by Thiols

• 7 P-H-Reagents as Tin Hydride Substitutes

• 8 Miscellaneous Examples

• 9 Summary and Outlook

defunctionalizations - reductions - radical reactions - silicon - tin

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