Intramolecular Cyclizations via Carbenoid Intermediates in Complexation of Alkynyltungsten Compounds with Co<sub>2</sub>(CO)<sub>8</sub>:  A New Route to the Pauson−Khand Reaction ShiuYung-Tai MadhushawReniguntala J. LiWen-Tai LinYin-Chih LeeGene-Hsian PengShie-Ming LiaoFeng-Lin WangSue-Lang LiuRai-Shung 1999 Intramolecular Cyclizations via Carbenoid Intermediates in Complexation of Alkynyltungsten Compounds with Co<sub>2</sub>(CO)<sub>8</sub>:  A New Route to the Pauson−Khand Reaction