Ferrocenylphosphines as New Catalysts for Baylis−Hillman Reactions

Abstract

[reaction: see text] Readily available ferrocenyldialkylphosphines are effective air-stable catalysts for Baylis-Hillman reaction between aldehydes and acrylates, affording the corresponding adducts in high yields and short reaction times. A set of readily accessible planar chiral ferrocenyldialkylphosphines have been tested in asymmetric Baylis-Hillman reactions. The best enantioselectivities were obtained using Mandyphos as chiral catalyst (up to 65% ee).

Enantioselective Phosphine Organocatalysis

“…Moreover, chiral diphosphines may totally lose their discriminating ability when lacking the chelated arrangement they usually display in the coordination sphere of a metal. Thus, it is not really surprising that screenings of commercially available chiral phosphines, such as atropisomeric diphosphines, [14][15][16] 1,2-bis[2-anisyl(phenyl)phosphino]ethane (DIPAMP), [17][18][19] 4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolane (DIOP), 18 and others, [20][21][22] in organocatalytic processes met with only moderate success in terms of catalytic activity and enantioselectivity. Notable exceptions are represented by bidentate phosphines, such as 1,2-bis(2,5-diethylphospholano)ethane (Et-BPE), 23 1,2-bis(2,5-diethylphospholano)benzene (Et-DuPHOS), 24 and BI-NAPHANE, 25 which because of their cyclic structures can be legitimately included in one of the two classes of wellsuited phosphorus organocatalysts, known so far.…”

Lewis‐Base‐Katalyse in der organischen Synthese

“…So lieferte die Umsetzung von Acrylaten mit aromatischen und aliphatischen Aldehyden in Gegenwart des Ferrocenylphosphans 63 ohne Brønsted-Säure-Cokatalysator nach kurzen Reaktionszeiten die zugehörigen Additionsprodukte in hohen Ausbeuten (Schema 20). [108] Die wichtigsten Fortschritte in der asymmetrischen Morita-Baylis-Hillman-Reaktion gehen zwar auf difunktionelle Katalysatoren zurück, es wurden aber auch einige neue Synthesemethoden mit reinen Lewis-Base-Katalysatoren entwickelt. [109] In den letzten Jahren galt den Rahut-CurrierCyclisierungen ein zunehmendes Interesse.…”

Catalytic Asymmetric Baylis–Hillman Reactions and Surroundings

“…Chiral ferrocenylphosphines 95 were investigated by Pereira and coworkers [63] in the asymmetric Baylis-Hillman reaction between p-nitrobenzaldehyde and benzylacrylate. Chiral catalyst 95, which combined both planar and central chirality, gave the Baylis-Hillman adducts in 78% yield and 65% ee (Scheme 10.49).…”