1: 4-Iodo-piperidine-1-carboxylic acid,tert-butyl ester With ethylene dibromide; zinc in tetrahydrofuran 2: With chloro-trimethyl-silane in tetrahydrofuran 3: 2-iodopyrazine With trifuran-2-yl-phosphane; tris(dibenzylideneacetone)dipalladium (0) T=80°C; Further stages.;