In the past few weeks of class we have been learning about a reaction called the Diels Alder reaction.
A Diels Alder reaction is an
organic chemical reaction between a conjugated diene and a substituted alkene.
The substituted alkene is commonly known as a dienophile. When these two react,
a cyclohexene will always form. Otto Paul Hermann Diels and Kurt Alder first
described this reaction in 1928. This reaction occurs via a single cyclic
transition state. No intermediates occur during the reaction. As concerted
cycloadditions, these reactions are stereospecific. A simple Diels-Alder reaction can be seen in the
following video below (1).
These Diels-Alder reactions can be seen in nature. One example
that was found in research done by Princeton University was Solanapyrone A. As
stated in the research, Solanapyrone A is “ a decalin polyketide phytotoxin
produced by the pathogenic fungus Alternaria solani, causal organism of potato
early blight disease.” This is an intermolecular reaction that resulted with a
2:1 ratio of the endo product to the exo product (2). This reaction can be seen
below.
http://www.princeton.edu/~orggroup/supergroup_pdf/da_ase_lowres.pdf
Overall,
Diels-Alder reactions are a reaction between a diene and a dieneophile. These
reactions also result in a cyclohexene with no intermediates during the process.
Solanapyrone A helps to show that these reactions surround us in nature. For
more information on Diels-Alder reactions check out chapter 16 in the text book
Organic Chemistry 3rd edition by Janice Gorzynski Smith.
References:
1.
The
diels-alder cycloaddition.
(n.d.). Retrieved from
Alder_Cycloaddition
2.
Drhal, C.
(2005). Evidence for enzymatic catalysis of the diels-alder reaction in
nature. In Organic
Supergroup LiteratureRetrieved from
http://www.princeton.edu/~orggroup/supergroup_pdf/da_ase_lowres.pdf
