Solvent-controlled diastereoselective synthesis of cyclopentane derivatives by a [3 + 2] cyclization reaction of alpha,beta-disubstituted (alkenyl)(methoxy)carbene complexes with methyl ketone lithium enolates.
Reaction of alpha,beta-unsaturated methoxycarbene complexes 1 and 11 with methyl ketone lithium enolates 2 leads to the corresponding five-membered carbocyclic compounds 4 or diast-4 and 12. The influence of the solvent and/or cosolvent (PMDTA), which turned out to be crucial to direct the reaction to 4 or diast-4, is studied, and a tentative mechanism according to these facts is proposed. In addition, the reaction of carbene complex 1a with alkynyl methyl ketone lithium enolates can be directed to the formal [3 + 2] or [4 + 1] cyclization products by a slight variation of the reaction conditions. Finally, consecutive three-component coupling reactions with carbene complex 1a, lithium enolates 2, and aldehydes 18 to give, in a diastereoselective way, hydroxy carbonyl compounds 19 and tricyclic polyethers 20 are presented.
Barluenga
José
J
Instituto Universitario de Química Organometálica Enrique Moles, Unidad Asociada al CSIC, Universidad de Oviedo, Julián Clavería 8, 33071-Oviedo, Spain. barluenga@sauron.quimica.uniovi.es
Alonso
Jorge
J
Fañanás
Francisco J
FJ
D000447:Aldehydes / Q000737:chemistry; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D006838:Hydrocarbons; D007659:Ketones / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D012997:Solvents; D013237:Stereoisomerism
D000447:Aldehydes; D003517:Cyclopentanes; D006838:Hydrocarbons; D007659:Ketones; D009942:Organometallic Compounds; D012997:Solvents; C030011:carbene; D008094:Lithium; D008697:Methane