Chromium / Carbene complexes / N-ylide complexes / Thio and selenophenols / Acetic acid / Acetic acid Aminocarbene complexes of chromium 1b-d react triple bond, synthesis of functionalized 2-oxohexahydroindole 11 was achieved. In the case of acetic acid, successively with diphenylacetylene, XH (X = PhS, PhSe, OAc) and finally with pyridine to give a series of products resulting from a formal protonation/hydride addition reaction together with a carbon-nitrogen bond functionalized pyrrolinones 7 via N-ylide complexes 2. The X-ray structure of 7b originating from a ring-opening rupture were also observed besides protonation/ dealkylation products. reaction could be established. When this sequence was applied to the aminocarbene complex 8 bearing a tethered result of a C-protonation followed by demethylation at the [ ] Part XI: Ref. as protonation/dealkylation agents, we first attempted the [a] Laboratoire de Synthe `se Organique et Organome ´tallique, reaction of thiophenol with complex 2a. Thus, when 2a was UMR 7611, Tour 44-45 refluxed in benzene in the presence of an excess of thio-E-mail: