One‐pot Synthesis of 1,3‐Butadiene and 1,6‐Hexanediol Derivatives from Cyclopentadiene (CPD) via Tandem Olefin Metathesis Reactions

Abstract A novel tandem reaction of cyclopentadiene leading to high value linear chemicals via ruthenium catalyzed ring opening cross metathesis (ROCM), followed by cross metathesis (CM) is reported. The ROCM of cyclopentadiene ( CPD ) with ethylene using commercially available 2 nd gen. Grubbs metathesis catalysts ( 1‐G2 ) gives 1,3‐butadiene ( BD ) and 1,4‐pentadiene ( 2 ) (and 1,4‐cyclohexadiene ( 3 )) with reasonable yields (up to 24 % ( BD ) and 67 % ( 2 + 3 ) at 73 % CPD conversion) at 1–5 mol % catalyst loading in toluene solution (5 V% CPD , 10 bar, RT) in an equilibrium reaction. The ROCM of CPD with cis ‐butene diol diacetate ( 4 ) using 1.00 ‐ 0.05 mol % of 3 rd gen. Grubbs ( 1‐G3 ) or 2 nd gen. Hoveyda‐Grubbs ( 1‐HG2 ) catalysts loading gives hexa‐2,4‐diene‐1,6‐diyl diacetate ( 5 ), which is a precursor of 1,6‐hexanediol (an intermediate in polyurethane, polyester and polyol synthesis) and hepta‐2,5‐diene‐1,7‐diyl diacetate ( 6 ) in good yield (up to 68 % or TON: 1180). Thus, convenient and selective synthetic procedures are revealed by ROCM of CPD with ethylene and 4 leading to BD and 1,6‐hexanediol precursor, respectively, as key components of commercial intermediates of high‐performance materials.