DABCO Cyclic tertiary amine catalyst

DABCO 8154 Cyclic tertiary amine catalyst Air Products and Chemicals, Inc. 

Cyclic tertiary amine catalyst, 508 DABCO K-15 Metallic based catalyst, 508 Darocure 1173... 

The Baylis-Hillman (also called Morita-Baylis-Hillman) (MBH) reaction (see Sect. 10.2.4 and Scheme 10.17) is the base-catalyzed addition of keto compounds to acrylic derivatives. The catalyst is a cyclic tertiary amine such as 1,4-diazabicyclo[2.2.2]octane (DABCO). Due to the generally poor yields observed, the reaction has not received sufficient attention despite the great synthetic value of the polyfunctional adducts. Among the various methods proposed to activate the reaction, pressure 107] and hydrophobic effects [70] have been used. Table 10.31 presents the results obtained in some Baylis-Hillman reactions carried out under pressure in aqueous solution [108]. 

Heteroaromatic aldehydes are excellent electrophiles in the MBH reaction because of their increased electrophilicity. The heteroatom also facilitates the proton transfers involved in the reaction (Scheme 1.53)/ In the presence of DABCO, pyridine-2-carboxaldehyde derivatives react rapidly with acrylates, methyl vinyl ketone and acrylonitrile to give excellent yields of the MBH adducts 112, which can be further transformed into indolizines 114 by thermal cyclization of their acetate derivatives 113 (Scheme 1.54)/ Notably, a small amount of indolizine 114 was formed along with normal MBH adduct 112 in the reaction of pyridine-2-carboxaldehyde with methyl vinyl ketone. Similarly, substituted 2-chloronicotin aldehydes 115 are reactive and efficient in the MBH reaction of methyl acrylates, acrylonitrile and cyclic enones catalyzed by various tertiary amine catalysts, such as DABCO, DBU, imidazole and 1-methylimidazole, to provide novel MBH adducts 116 and 117 for biological activity screening (Scheme 1.55). ... 

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