Recent studies on samarium diiodide mediated organic synthesis

Abstract

This article summarizes the results of our recent studies on development of new reactions with samarium diiodide utilizing its characteristic reactivities. The reactions dealt in this article include novel carbon-carbon bond forming reactions of both intramolecular and intermolecular types, and functional group transformations. Also, some examples of asymmetric synthesis by intermolecular pinacol coupling reactions and hydrodimerization of alpha,beta-unsaturated carbonyl compounds are presented here. 1 Introduction 2 Reactions Involving Intermolecular C-C Bond Formation 2.1 Coupling Reaction of Isothiocyanates or Isocyanates with SmI2 2.2 A Facile Synthesis of 4-Hydroxy-(E)-alkenoic Esters 2.3 Highly Diastereoselective Intermolecular Pinacol Coupling Reactions 2.4 Asymmetric Hydrodimerizations of alpha,beta-Unsaturated Carbonyl Compounds 2.5 A Novel C-C Bond Formation Process Mediated by SmI2: Effective Approach to Baylis-Hillman Adducts 3 Reactions Involving Intramolecular C-C Bond Formation 3.1 Reductive Intramolecular Cyclization of alpha-Bromo Silyl Ethers 3.2 Intramolecular Reductive Cyclization of beta-Ketoisothio-cyanates Promoted by Samarium Diiodide 4 Reactions Proceeding without the Formation of a C-C Bond 4.1 Novel Reduction of Isothiocyanates to Thioformamides with SmI2 4.2 A Convenient Coupling of Isocyanates with Tertiary Alcohols with a Catalytic Amount of SmI2 4.3 Efficient Synthesis of Iodohydrins by Selective Cleavage of Epoxides with Samarium Iodide Complex 4.4 Highly Regioselective Cleavages and Iodinations of Cyclic Ethers with SmI2 4.5 Facile Synthesis of Enol Ethers by Cleavage of alpha-Bromoacetals and alpha-Bromoketals Mediated by SmI2 5 Conclusion.