Diastereoselective multicomponent cyclizations of Fischer carbene complexes, lithium enolates, and allylmagnesium bromide leading to highly substituted five- and six-membered carbocycles.
The one-pot sequential reaction of a chromium alkoxycarbene complex, a ketone or ester lithium enolate, and allylmagnesium bromide enabled the selective synthesis of novel diastereomerically pure pentasubstituted cyclopentanols or tetrasubstituted 1,4-cyclohexanediols, depending on the degree of substitution at the Cbeta position of the enolate anion. A few exceptions have been encountered in which tetrasubstituted cyclopentanols or pentasubstituted 1,4-cyclohexanediols were selectively formed. The use of 2-iodoethoxycarbene complexes gave access to 1,2,4-cyclohexanetriols. These multicomponent-coupling reactions involved the formation of lithium alkylpentacarbonylchromates as key intermediates, which further evolved through intramolecular processes, such as insertion of an alkene, CO insertion or addition to a carbonyl group, and, moreover, could be trapped in intermolecular reactions with different electrophiles and styrene. The substitution pattern of the alkylchromate carbon chain has been proposed to control the nature of the annulation process.
Barluenga
José
J
Instituto Universitario de Química Organometálica "Enrique Moles", Unidad Asociada al CSIC, Universidad de Oviedo Julián Clavería 8, 33006 Oviedo, Spain. barluenga@uniovi.es
Pérez-Sánchez
Iván
I
Suero
Marcos G
MG
Rubio
Eduardo
E
Flórez
Josefa
J
D000438:Alcohols / Q000138:chemical synthesis; D000498:Allyl Compounds / Q000737:chemistry*; D001965:Bromides / Q000737:chemistry; D003500:Cyclization; D003510:Cyclohexanes / Q000138:chemical synthesis*; D003517:Cyclopentanes / Q000138:chemical synthesis*; D006838:Hydrocarbons / Q000737:chemistry; D008094:Lithium / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D013237:Stereoisomerism
D000438:Alcohols; D000498:Allyl Compounds; D001965:Bromides; D003510:Cyclohexanes; D003517:Cyclopentanes; D006838:Hydrocarbons; D009942:Organometallic Compounds; C016327:cyclopentanol; C030011:carbene; D008094:Lithium; D008274:Magnesium; D008697:Methane