Acrolein nucleophilic addition reactions

This reaction is the acid-catalyzed counterpart of a 1,4-addition reaction to an a,l3-unsaturated carbonyl compound. Chloride ion, without an acid present, will not add to acrolein. That is, chloride ion is not a strong enough nucleophile to drive the reaction to the right. However, if the carbonyl is protonated, the intermediate cation is a stronger electrophile and will react with chloride ion. 

It is curious to note that fV-CBA-inactivated MAO continues to produce acrolein at pH 7, but at pH 9 incorporates up to 40 equivalents of acrolein into the protein in a time-dependent manner. The increased incorporation at higher pH is consistent with the ionization of nucleophilic groups that partake in Michael addition reactions with the liberated acrolein. The continued production of acrolein after complete inactivation results from reactivation-inactivation cycling of the enzyme by the iV-CBA inhibitor (103). However, with 7Y-(l-methyl)cyclopropyIbenzylamine, the inactivated and reduced enzyme does... 

Two synthetic routes predicted by LHASA for the synthesis of quinoline (24) are shown in Scheme 7. LHASA S first synthetic route was to have 2-amino-benzaldehyde (25) condense with acetaldehyde (26) to yield quinoline and water, which is essentially equivalent to the known synthesis of quinoline from the reaction of aniline with acetaldehyde and formaldehyde (77). When this transform was removed from consideration, LIMS A suggested nucleophilic addition of aniline (27) to acrolein (28) to yield quinoline and water, which is identical to a known synthesis of quinoline (75). 

As described in the preceding sections, many domino reactions start with the formation of vinyl palladium species, these being formed by an oxidative addition of vinylic halides or triflates to Pd°. On the other hand, such an intermediate can also be obtained from the addition of a nucleophile to a divalent palladium-coordinated allene. Usually, some oxidant must be added to regenerate Pd11 from Pd° in order to achieve a catalytic cycle. Lu and coworkers [182] have used a protonolysis reaction of the formed carbon-palladium bond in the presence of excess halide ions to regenerate Pd2+ species. Thus, reaction of 6/1-386 and acrolein in the presence of Pd2+ and LiBr gave mainly 6/1-388. In some reactions 6/1-389 was formed as a side product (Scheme 6/1.98). 

In fact, a mechanism for this reaction can be drawn that does not involve Pd at all, but let s assume that Pd is required for it to proceed. Cl- must be nucleophilic. It can add to Cl of the alkyne if the alkyne is activated by coordination to Pd(II). (Compare Hg-catalyzed addition of water to alkynes.) Addition of Cl- to an alkyne-Pd(II) complex gives a o-bound Pd(II) complex. Coordination and insertion of acrolein into the C2-Pd bond gives a new a-bound Pd(II) complex. In the Heck reaction, this complex would undergo P-hydride elimination, but in this case the Pd enolate simply is protonated to give the enol of the saturated aldehyde. 

Attyl and propargyl group transfer. Sulfinic acids or their sodium salts assist Pd(0)-catalyzed deallylation by accepting the allyl group. In addition to allylic esters, allylic sulfoximines can also deliver the allyl group to nucleophiles such as amines. Acrolein acetals react with 1,3-dicarbonyl compounds but the regiochemistry is strongly dependent on reaction temperatures. ... 

The conjugate addition of oxygen nucleophiles to acceptor-substituted olefins is the oxa-Michael reaction (Scheme 15). The term is derived from heteroatom replacement nomenclature, meaning that oxygen takes the place of a CH2 unit (RCH2 RO ). Oxa-Michael reactions have been known for many years and are often catalyzed by bases or acids [7]. Catalysis by metals has been reported sporadically in the older literature, e.g. for the case of alcohol addition to vinyl ketones with a Nieuwland catalyst (HgO, BF3-OEt2, ROH) [75-77]. A patent describes a PdCl2-catalyzed addition of alcohols to acrolein or methacrolein [78]. 

We have spectroscopic evidence that a conjugated C=C bond is polarized, and we can explain this with curly arrows, but the actual bond-forming step must involve movement of electrons from the HOMO of the nucleophile to the LUMO of the unsaturated carbonyl compound. This example is an efficient (the reaction happens even at 0 °C) addition to acrolein (prop-enal) with methoxide as the nucleophile. 

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