But-3-enal

Butanone, see Methyl ethyl ketone (MEK) trans-But-2-enal — ... 

Of the simpler examples, the formation of a 2-methylchromene and a fiav-3-ene from the reaction of 2,4-dihydroxyacetophenone with but-2-enal and cinnamaldehyde, respectively, are worthy of mention (7lJCS(C)81l). 

Fig. 5.12. HPLC separation of a reference mixture of alk-2-enals. The numbers indicate the chain length of the aldehyde, thus 4 but-2-enal 5 pent-2-enal etc. (Benedetti et...

Addition of sodium ethanethiolate to 3-chloro-4,4,4-trifluoro-2-phenylbut-2-cnal (23) furnishes the substituted but-2-enal derivative 24 in good yield. 

The mechanism of many condensation reactions has been shown to comprise consecutive ADDITION and elimination reactions, as in the base-catalyzed formation of fEj-but-2-enal (crotonaldehyde) from acetaldehyde, via 3-hydroxybutanal (aldol). The overall reaction in this example is known as the aldol condensation. 

But-2-enedinitrile, 2-nitropropene, phenyl vinyl sulfoxide, styrene and but-2-enal do not form 1-methoxy-l -phenylcyclopropanes with the corresponding chromium-carbene complex. " On the other hand, methyl vinyl ketone gave a formal 1,4-adduct, which, due to its instability, was further transformed under acidic conditions. ... 

Compared with the naked nickel reactions, reactions with phosphane-modified nickel catalysts require higher temperatures (80-100 C) in order to proceed at a reasonable rate and usually exhibit a decreased stereoselectivity. Despite these obvious drawbacks, such catalyst systems are advantageous in the case of highly electron-deficient alkenes, such as ( )-but-2-enal. ° or dialkyl fumarates, which can be readily employed as cycloaddition substrates only with modified nickel catalysts (vide supra). 

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