Multiple Pd-catalyzed reactions in the synthesis of natural products, drugs, and materials.

The efficient synthesis of natural products, drugs, and materials with economical and ecological advantages is a very important goal in modern synthetic chemistry. In such an approach, toxic substrates as well as reagents have to be avoided, the amount of waste has to be reduced, and the exploitation of our resources has to be diminished. In this respect, the use of catalytic processes is highly advantageous; however, even more beneficial is the combination of several catalytic processes either in a sequential or, more efficiently, in a domino mode. In this article, the synthesis of several natural products, drugs, and materials is described, employing multiple Pd-catalyzed processes either in a sequential or a domino fashion. Based on a double-Heck reaction developed by us for the preparation of estradiol, the efficient synthesis of the highly potent contraceptive desogestrel is discussed; for the synthesis of α-tocopherol and diversonol an enantioselective domino-Wacker/Heck reaction was utilized, whereas in the case of diversonol, a domino-Wacker/carbonylation was even more effective, and several molecular switches containing a helical tetrasubstituted double bond were prepared employing a domino-carbopalladation/Stille reaction. Finally, acenaphthylenes could be obtained by a domino-carbopalladation/C-H-activation. [ABSTRACT FROM AUTHOR]