Cyclopropyl building blocks for organic synthesis, part 97. Convenient route to 2-(trialkylstannyl)cyclopropylamines and their application in palladium-catalyzed cross-coupling reactions

The 2-(trialkylstannyl)-N,N-dialkylcyclopropylamines 3 were obtained by titanium-mediated aminocyclopropanation of tributylvinylstannane with N,N-dialkylformamides in yields of 80-84% and with excellent diastereoselectivities (trans/cis > 45:1). The resulting stannanes could advantageously be applied in Stille cross-coupling reactions with aryl iodides, providing the pure trans-2-aryl-(N,N-dialkylamino)cyclopropanes 8 in yields ranging from 45 to 67% (six examples). The coupling of ethyl (E)-3-iodoacrylate (9) gave ethyl cis-5-(dibenzylamino)cyclopent-2-enecarboxylate (10) as a single diastereomer in 54% yield. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).