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

Rapid and versatile access to ( Z )‐trisubstituted olefins 2 and their cyclization into 4‐aryl‐2 H ‐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‐2 H ‐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 .