Catalytic oxyselenenylation-deselenenylation reactions of alkenes - Stereoselective one-pot conversion of 3-alkenols into 2,5-dihydrofurans

A stereoselective multi-step one-pot procedure for converting 2-methoxycarb onyl-3-alkenols into 3-methoxycarbonyl-2,5-dihydrofurans, using only cataly tic amounts of diphenyl diselenide and an excess of ammonium persulfate, ha s been developed. The erythro alkenols give the trans dihydrofurans, while the three stereoisomers give the corresponding cis products. The configurat ions of the starting alkenols were deduced from those of the intermediate p henylseleno tetrahydrofurans, which were independently obtained from reacti ons of the alkenols with stoichiometric amounts of phenylselenenyl sulfate.