Platinum pincercomplexes featuring an SCS indenediide backbone have been prepared and evaluated in the catalyticcycloisomerization of alkynoic acids and N‐tosyl alkynylamides. One of the platinum complexes significantly outperforms its palladium analogue for the formation of 6‐ and 7‐membered rings. The catalytic system takes advantage of the alkynophilicity of Pt and of the non‐innocent character
New SCS Pd pincercomplexes featuring a noninnocent indenediide backbone show high catalytic activity in cycloisomerization. A variety of alkylidenelactams (five- to seven-membered rings) have been prepared efficiently from N-tosyl alkynylamides, and good results have also been obtained with challenging alkynoic acids.
1a–c are shown to very efficiently catalyze the cycloisomerization of alkynoicacids into alkylidenelactones via metal–ligand cooperation (TON up to 2000). Complexes 1a–c are competent toward a broad range of alkynoicacids, including functionalized and internal ones, and give access to 5- as well as 6- and 7-membered lactones in excellent yields and with very high selectivities.