Synthesis of Six-Membered Rings Diels-Alder Reaction

SYNTHESIS OF SIX-MEMBERED RINGS (DIELS-ALDER REACTION) 

The Diels-Alder reaction (for which Otto Diels and Kurt Alder were awarded together the Nobel Prize in 1950) involves the reaction of a conjugated diene with another group containing a pi bond (referred to as a dienophile since it loves reacting with dienes). In the presence of heat, a diene and a dienophile will combine to give a cyclohexene product. This concerted mechanism is an example of a pericyclic reaction called a [4 -i- 2] cycloaddition since it involves the interaction of a four-electron % system (the diene) with a two-electron 71 system (the dienophile). While many examples of the Diels-Alder reaction can be easily described as a reaction between a nucleophile and electrophile (the approach to be taken here), the mechanism and the regjo- and stereochemistry of the product is usually described by frontier orbital theory in which the HOMO of the diene and the LUMO of the dienophile are matched. 

Introduction to Strategies for Organic Synthesis, Ynst Edition. Laurie S. Starkey. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

It should be noted that the aza Diels-Alder and oxo Diels-Alder reactions involve nitrogen- and oxygen-containing components, respectively, to give a variety of six-membered heterocyclic compounds. This book will only address the traditional, all-carbon Diels-Alder reaction. 

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