First Total Synthesis and Structural Confirmation of C13‐Butylrubber Oligomers

The first total synthesis of an important C13 butyl rubber oligomer is reported. The structure of the oligomer, which is an important and potentially toxic extractable and leachable component of elastomeric closures, is confirmed by synthesis for the first time. The method described is scalable, making large quantities of the oligomer available for the first time for AMES toxicity studies. The challenging synthesis commences with isophorone and the key steps of the synthesis involve the development of highly novel dithoacetal chemistry, cuprate addition and Tebbe olefination.The first total synthesis of important C13 butyl rubber oligomers is reported. The structure of the oligomer, which is an important extractable and leachable component of elastomeric closures, is confirmed for the first time. The 10‐step synthetic sequence starting from isophorone is robust and scalable, making large quantities of the oligomer available for the first time