Efficient access to sp(3)-rich tricyclic amine scaffolds through Diels-Alder reactions of azide-containing silyloxydienes

The preparation of sp(3)-rich scaffolds to obtain more natural product-like libraries for incorporation into screening decks is challenging. Here, we describe the use of a Diels-Alder reaction between an enone and an azide-containing silyloxydiene to gain efficient access to complex tricyclic amine scaffolds. Derivatization of these scaffolds provided a library of 80 amines, amides, sulfonamides, quinolines and indolenines, all in >20 mg quantities and >90% purities. These library compounds displayed properties more similar to alkaloid natural products than to drugs and commercial drug-like libraries, as shown by a high proportion of sp(3) carbon centers.