The key step in our 3-benzylpyrrolidine synthesis was to be the zirconocene-mediated co-cyclisation of 1-aryl-4-aza-1,6-dienes 4. We needed a synthesis of 4, which was reasonable for library synthesis, including on a solid phase. The usual route, alkylation of an allylamine with a cinnamyl bromide, works well in solution but the large excess needed to drive the reaction to completion on a solid phase would lead to over-alkylation. It is also not suitable for library synthesis ...
