Chemical synthesis is one of the key technologies underlying modern drug discovery and development. For the design and accessibility of novel structures and the rapid preparation of new test compounds and development candidates with often highly complex chemical architecture, it is essential to use state-of-the-art chemical synthesis technologies. Recent developments in the field of asymmetric catalysis point to a third class of catalysts besides the established enzymes and metal complexes, so-called organocatalysts. These low-molecular-weight, organic molecules enable highly chemo- and stereoselective chemical transformations for the rapid assembly of complex bioactive molecules of interest for the pharmaceutical industry.

This book presents the contributions from leading experts, with backgrounds in academia and industry, to an Ernst Schering Research Foundation Symposium held in April 2007. It illustrates current progress in organocatalysis in functional group interconversions, organocatalytic CC- and CX-bond formations with small molecules as well as peptide-based catalysts and genetically engineered enzymes and their applications in natural product and drug syntheses. It will be of interest to those who want a general overview of the topic, but also to those who want to learn more about the state of the art, current trends and perspectives in this highly dynamic field of research.

As nucleophiles, simple alkenes are typically so unreactive that only highly active electrophiles, such as carbocations, peroxides, and halogens will react with them. For the generation of carbon-carbon bonds, milder methods will often be required. Fortunately, it is possible to increase the reactivity of alkene-type p-nucleophiles by introducing electron-donating substituents. Substitution of one H with an OH or OR gives an enol or a vinyl ether, which are already much better nucleophiles. Using nitrogen instead of oxygen, one obtains even better nucleophiles, enamines. Enamines are among the most reactive neutral carbon nucleophiles, exhibiting rates that are even comparable to some charged nucleophiles, such as enolates [1, 2]. Most enamines, unfortunately, are sensitive to hydrolysis. The parent enamine, N,N-dimethylvinylamine, has in fact been prepared [3], but appears to be uns- ble. Enamines of cyclic ketones and many aldehydes can readily be isolated, however [4-7]. The instability of enamines might at first appear to diminish the utility of enamines as nucleophiles, but actually this property can be viewed as an added benefit: enamines can be readily and rapidly generated catalytically by using a suitable amine and a carbonyl compound. The condensation of aldehydes or ketones with amines initially affords an imine or iminium ion, which then rapidly loses a proton to afford the corresponding enamine (Scheme 1).

As nucleophiles, simple alkenes are typically so unreactive that only highly active electrophiles, such as carbocations, peroxides, and halogens will react with them. For the generation of carbon-carbon bonds, milder methods will often be required. Fortunately, it is possible to increase the reactivity of alkene-type p-nucleophiles by introducing electron-donating substituents. Substitution of one H with an OH or OR gives an enol or a vinyl ether, which are already much better nucleophiles. Using nitrogen instead of oxygen, one obtains even better nucleophiles, enamines. Enamines are among the most reactive neutral carbon nucleophiles, exhibiting rates that are even comparable to some charged nucleophiles, such as enolates [1, 2]. Most enamines, unfortunately, are sensitive to hydrolysis. The parent enamine, N,N-dimethylvinylamine, has in fact been prepared [3], but appears to be uns- ble. Enamines of cyclic ketones and many aldehydes can readily be isolated, however [4-7]. The instability of enamines might at first appear to diminish the utility of enamines as nucleophiles, but actually this property can be viewed as an added benefit: enamines can be readily and rapidly generated catalytically by using a suitable amine and a carbonyl compound. The condensation of aldehydes or ketones with amines initially affords an imine or iminium ion, which then rapidly loses a proton to afford the corresponding enamine (Scheme 1).

Chemical synthesis is one of the key technologies underlying modern drug discovery and development. For the design and accessibility of novel structures and the rapid preparation of new test compounds and development candidates with often highly complex chemical architecture, it is essential to use state-of-the-art chemical synthesis technologies. Recent developments in the field of asymmetric catalysis point to a third class of catalysts besides the established enzymes and metal complexes, so-called organocatalysts. These low-molecular-weight, organic molecules enable highly chemo- and stereoselective chemical transformations for the rapid assembly of complex bioactive molecules of interest for the pharmaceutical industry.

This book presents the contributions from leading experts, with backgrounds in academia and industry, to an Ernst Schering Research Foundation Symposium held in April 2007. It illustrates current progress in organocatalysis in functional group interconversions, organocatalytic CC- and CX-bond formations with small molecules as well as peptide-based catalysts and genetically engineered enzymes and their applications in natural product and drug syntheses. It will be of interest to those who want a general overview of the topic, but also to those who want to learn more about the state of the art, current trends and perspectives in this highly dynamic field of research.