Zirconocene-promoted synthesis of substituted tetrahydropyrans

Zirconocene reagents derived from zirconocene dichloride and two equivalents of butyllithium react with allylic, homoallylic diene ethers. Hydrolysis of the reaction products yields substituted tetrahydropyrans. The reaction is postulated to occur via cyclization of the diene to form a zirconacyclopentane. This cyclization occurs without allylic rearrangement.     

Robust Microporous Metal–Organic Frameworks for Highly Efficient and Simultaneous Removal of Propyne and Propadiene from Propylene

Simultaneous removal of trace amounts of propyne and propadiene from propylene is an important but challenging industrial process. We report herein a class of microporous metal–organic frameworks ( NKMOF‐1‐M ) with exceptional water stability and remarkably high uptakes for both propyne and propadiene at low pressures. NKMOF‐1‐M separated a ternary propyne/propadiene/propylene (0.5 : 0.5 : 99.0) mixture with the highest reported selectivity for the production of polymer‐grade propylene (99.996 %) at ambient temperature, as attributed to its strong binding affinity for propyne and propadiene over propylene. Moreover, we were able to visualize propyne and propadiene molecules in the single‐crystal structure of NKMOF‐1‐M through a convenient approach under ambient conditions, which helped to precisely understand the binding sites and affinity for propyne and propadiene. These results provide important guidance on using ultramicroporous MOFs as physisorbent materials.