Two different reactions were experimented for the construction of the eight-membered B-ring of taxane skeleton through the formation of the C9C10 bond. A SmI2 promoted radical reaction on seco-alkynyl aldehydes 11cis or 11trans failed. A Nozaki/Kishi reaction carried out on the seco-iodovinyl aldehyde 12trans led, through an unprecedented intramolecular SN2′ reaction, to the “abnormally” cyclised product