Use of Monoclonal Antibodies in Hetero Diels-Alder Reactions

Use of Monoclonal Antibodies in Hetero Diels-Alder Reactions 

Many examples of the use of catalytic monoclonal antibodies for a variety of organic transformations and especially for Diels-Alder reactions have been described in the last years since its discovery by Lerner and Schultz [563], Recently, a hetero Diels-Alder reaction of an arylnitroso dienophile 9-4 and ( )-piperylene 9-3 to give the two regioisomeric cycloadducts 9-5 and 9-6 in the presence of a catalytic antibody has been published by Pandit and his group [564]. The most successful hapten used was the bridged compound 9-7 (Fig. 9-2). 

There was a rate enhancement of kcat/kuncat= 1205 and also a slight change in the selectivity compared to the uncatalyzed reaction (9-5 9-6 uncatalyzed = 58 42 catalyzed = 47 53). 

A retro hetero Diels-Alder reaction to release an anthracene derivative 9-9 and nitroxyl (HNO) from the corresponding cycloadduct 9-8 by a catalytic antibody has been described by Reymond and Lerner [565]. As a haptene the acridinium salt 9-10 was used (Fig. 9-3). The antibody obtained is of great biological interest as a prodrug release system since the liberated nitroxyl is easily oxidized by the ubiquitous enzyme superoxide dismutase to give nitric oxide (NO) which acts as a chemical messenger for several important bioregulatory processes. 

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