DIRECT PREPARATION OF LANTHANOID ESTER HOMOENOLATES FROM 3-HALO ESTERS AND LANTHANOID METALS - THEIR HOMO-REFORMATSKY-TYPE REACTION WITH CARBONYL-COMPOUNDS

The direct reaction of ethyl 3-bromopropionate (2a) or 3-iodopropionate (2b) with lanthanoid metals (La, Ce, Nd, Sm) in tetrahydrofuran produces lanthanoid ester homoenolates (3), which react with ketones to give 7-lactones in good yields under mild conditions. The isolation of 3-phenylseleno (8a), 3-phenyltelluro (8b), and 3-tri-n-butylstannyl esters (10) from the reaction with diphenyl diselenide (7a), ditelluride (7b), and tri-n-butyltin iodide (9), respectively, suggests the formation of the lanthanoid ester homoenolate. © 1990, American Chemical Society. All rights reserved.