Synthesis of cis,syndiotactic-A-alt-B Copolymers from Enantiomerically Pure Endo-2-Substituted-5,6-Norbornenes

• Main Authors: Jang, Eun Sil (Contributor), John, Jeremy M (Contributor), Schrock, Richard Royce (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Chemistry (Contributor)
• Format: Article
• Language: English
• Published: American Chemical Society, 2018-03-27T19:02:04Z.
• Subjects: Article
• Online Access: Get fulltext

 Cis,syndiotactic A-alt-B copolymers, where A and B are two enantiomerically pure endo-2-substituted-5,6-norbornenes with "opposite" chiralities of the endo-2-substituted-5,6-norbornene skeleton, can be prepared using Mo(N-2,6-Me[subscript 2]C[subscript 6]H[subscript 3])(CHCMe[subscript 2]Ph)(OHMT)(pyrrolide) (1) as the initiator (OHMT = O-2,6-Mesityl[subscript 2]C[subscript 6]H[subscript 3]). Formation of a high percentage of A-alt-B dyads is proposed to rely on an inversion of chirality at the metal with each propagating step and a kinetically preferred diastereomeric relationship between a given chirality at the metal in propagating species and the chirality of the endo-2-substituted-5,6-norbornene skeleton. We also demonstrate that A-alt-B copolymers can be modified to give new variations which may not be accessible through direct copolymerization.