Palladium-catalysed reactions of aziridines and cyclopropanes

Strained-ring systems including vinylcyclopropanes, phenyl- and vinylaziridines were utilised to undergo ring-opening reactions under the catalysis of organotransition-metals in this research. Firstly, PdCl2(MeCN)2 catalysed the formal [3+2] annulations of N-activated aziridines to construct a number of potentially bioactive pyrroloindolines in one-pot with C3-substituted indoles. Furthermore, C3-unsubstituted indoles were treated with N-tosyl arylaziridines in the presence of PdCl2(MeCN)2 via a Friedel–Crafts pathway. The resulting β-substituted tryptamines then undergo the ring-closure with N-fluorobenzenesulfonimide to produce C3-fluorinated pyrroloindolines in moderate yields and selectivities. In chapter 2, the palladium(II)-catalysed addition of arylboronic acids to N-activated vinylaziridines has been developed. This reaction proceeds via a redox-neutral insertion/ring-opening process to provide unusual (Z)-allylsulfonamides preferentially. Finally, a highly efficient ring-opening reaction of vinylcyclopropanes by boronic acids was reported in the chapter 3, using palladium nanoparticles formed from Pd(OAc)2 and boronic acids in neat water. Linear and branched regioselectivities were obtained using vinylcyclopropanes and aryl-substituted vinylcyclopropanes respectively under these ligandless conditions.