A One-Pot Three-Step Synthesis of Z-Trisubstituted Olefins from Arylalkynes and Their Cyclization into 4-Aryl-2H-chromenes

International audienceRapid and versatile access to (Z)‐trisubstituted olefins 2 and their cyclization into 4‐aryl‐2H‐chromenes 1 starting fromarylalkynes 3 is described. In a one‐pot fashion, alkynes 3 were first hydrated, then transformed into N‐tosylhydrazones, and finally coupled with ortho‐substituted aryl halides under palladium catalysis to give trisubstituted olefins 2 in good yields and very high to total Z selectivity. 1,1‐Diarylolefins 2 having an ortho‐OMOM (methoxymethoxy) substituent underwent rapid cyclization in the presence of p‐toluensulfonic acid to give a variety of 4‐aryl‐2H‐chromenes in good to excellent yields. This methodology was also successfully applied to the preparation of 5‐aryl‐2,3‐dihydrobenzo[b]oxepine 4 from the required arylbutynol 3b