Reaction of Phosphonate-Stabilized Carbanions with Cyclic Enones Bearing a β-Leaving Group

Article abstract of DOI:10.1021/jo00130a024

Reaction between α-lithiated alkylphosphonic esters and α,β-unsaturated cyclopentenones and cyclohexenones carrying a heteroatom substituent Y in the β-position was studied.Complete chemoselectivity was observed as a function of substituent Y.For Y = OMe exclusive addition-elimination at the β-carbon was observed, yielding α,β-unsaturated δ-ketophosphonates.The β-chloro-substituted substrates (Y = Cl) derived from cyclohexenone reacted exclusively at the carbonyl carbon, yielding (2-hydroxyalkyl)phosphonates with the retained chlorovinyl function.The alcohols, depending on the conditions, could be dehydrated to two different products.The reaction of 3-chlorocyclopent-2-en-1-one with diethyl (lithiomethyl)phosphonate occured at the β-carbon, but the ketophosphonate product was isolated in a stable enolic form.