Domino Ring Opening—Ring Closing Metathesis (ROM—RCM) Strategy Toward Bicyclo[n.3.0]cycloalkenes.

Abstract

Metathesis reactionsMetathesis reactions O 0286 Domino Ring Opening-Ring Closing Metathesis (ROM-RCM) Strategy Toward Bicyclo[n.3.0]cycloalkenes. -This offers a convenient approach to bicyclo[3.3.0]octenes and bicyclo[4.3.0]nonenes, cis-and trans-fused systems are available. Protection of the OH group is necessary for successful reaction. Starting from the acrylate (VIII), only ring-opening metathesis takes place yielding the triene (IX). -(HAGIWARA*, H.; KATSUMI, T.; ENDOU, S.; HOSHI, T.; SUZUKI, T.; Tetrahedron 58 (2002) 33, 6651-6654; Grad. Sch. Sci. Technol., Niigata Univ., Ikarashi, Niigata 950-21, Japan; Eng.) -Jannicke 01-053

Hybrid Polymerization of Ring-Opening Metathesis and Cross-Metathesis for Polyolefins with Tunable Architectures

“…Four cyclooctene monomers with alkenyl (1a), allyl (1b), buten-4-yl (1c), and octen-8-yl (1d) substitutions were synthesized (Scheme 1) and polymerized under regular ROM condition (323 K with 2 M monomer concentration) with the second-generation Grubbs catalyst (G2). It has already been well established that the ROM of the alkenyl-substituted cycloolefins including norbornenes and 4,5,6,7-numbered cycloolefins would be suppressed by intramolecular RCM reaction via a tandem ROM-RCM route, 39,40 while monomers like 2-vinyl-5norbornenes could be polymerized. 41,42 Similarly, the metathesis reaction of monomer 1c could lead to the formation of 5-numbered rings (Figure S3), while for molecules 1a, 1b, and 1d, their metathesis reactions presented significantly different behaviors with ROM of the olefin ring accompanied by terminal olefin participated CM, indicating that the formation of 3-, 4-, or 9-numbered ring was not favored for RCM (see Figures S1, S2, and S4 for corresponding characterizations).…”