DMAP-catalyzed hydroxymethylation of 2-cyclohexenones in aqueous medium through Baylis-Hillman reaction

DABCO oder DMAP – worauf beruht ihr Unterschied in der Organokatalyse?

“…[1,15,16] Wenn die Reaktivität allerdings von der Geschwindigkeit des nucleophilen Angriffs des Organokatalysators oder von der Freisetzung der Amin-Komponente im letzten Schritt der Reaktion abhängt, werden DABCO (1) und Chinuclidin (2) überlegen sein. [1,15,16] Der Befund, dass Baylis-Hillman-Reaktionen von Cycloalkenonen und Acrylaten besser durch DMAP (3) als durch den Standard-Katalysator DABCO (1) katalysiert werden, [17] spiegelt möglicherweise die Notwendigkeit höhe-rer Konzentrationen der zwitterionischen Intermediate bei diesen Reaktionen wider. Die Relevanz der hier ermittelten kinetischen und thermodynamischen Parameter für Acylierungsreaktionen ist derzeit noch unbekannt.…”

Cyclic Enones as Substrates in the Morita–Baylis–Hillman Reaction: Surfactant Interactions, Scope and Scalability with an Emphasis on Formaldehyde

“…Comparable or slightly lower yields to those reported [7,8,9,10] were observed in the case of the reaction of cyclohexenone with formaldehyde (i.e., 3). However, the reaction rate increase was quite significant with the SDS reaction being complete in under 1 hour (65%) as compared to multiple hours or more commonly days for known literature procedures.…”

“…Initial efforts concentrated on two protocols [that is, 1) DMAP/60 8C/5 days/68% and 2) imidazole/room temperature/17 days/93%] reported by El Gaïed, [7,8] for the conversion of 5,5-dimethylcyclohexenone to the corresponding MBH product. However, translation (and modification) of these conditions to substrate 6 gave at best yields of 4 in the range of 30%.…”

4-Dimethylamino-pyridine(DMAP)

“…It is well known that DMAP does not only serve as a catalyst for acylation reactions and (trans-) esterifications 7 but also for various organic transformations like the Baylis-Hillman reaction, 8 the Dakin-West reaction, 9 the protection of amines, 10 C-acylations, 11 silylations, 5 applications in natural products chemistry, 12 and many others. (B) A new efficient and simple route for the functionalization of nitrogen atoms using DMAP (i.e.…”

“…The hydromethylation of cyclohexenones with aqueous formaldehyde by the Baylis-Hillman reaction is catalyzed by DMAP or 4-(pyrrolidino)pyridine, whereas DABCO is not suitable in this case for steric reasons. 8 (D) Treatment of 9 with N-triflyl-4-(dimethylamino)pyridinium triflate enables a new approach to substituted cyclohexenones 10. This reagent is easily formed from DMAP and triflic anhydride, and is used in a 10-fold excess.…”