Reactions of carbonyl compounds with benzyl chloromethyl ether of diiodomethane in the presence of samarium(II) iodide or metallic samarium. New routes to 1,2-diols, iodohydrins and cyclopropanols

Carbonyl compounds react with benzyl chloromethyl ether in the presence of samarium(II) iodide to afford the corresponding addition products which, when subsequently hydrogenolysed, yield 1,2diols. Simple aldehydes and ketones react with diiodomethane in the presence of samarium metal to give iodohydrins in good yields. Under similar reaction conditions, α-halogeno substituted ketones and aromatic 1,4-diketones are converted into cyclopropanols. These cyclopropanations have been shown to proceed through the initial generation of samarium enolates, followed by the Simmons Smith type reaction. A novel transformation of esters to cyclopropanols via tandem one-carbon homologation is also described.