Z-selective olefin metathesis processes catalyzed by a molybdenum hexaisopropylterphenoxide monopyrrolide complex.
The molybdenum-based monoaryloxide monopyrrolide (MAP) species, Mo(NAd)(CHCMe(2)Ph)(C(4)H(4)N)(HIPTO) (2a), which contains "small" imido (Ad = 1-adamantyl) and "large" aryloxide (HIPTO = O-2,6(2,4,6-i-Pr(3)C(6)H(2))C(6)H(3)) ligands, catalyzes Z-selective metathesis reactions as a consequence of intermediate metallacyclobutane species not being able to have an (anti) substituent pointing toward the HIPTO group. Ring-opening metathesis polymerization (ROMP) of dicarbomethoxynorbornadiene (DCMNBD) with 2% 2a in toluene leads to >99% cis and >99% syndiotactic poly(DCMNBD), while ROMP of cyclooctene and 1,5-cyclooctadiene (300 equiv) with initiator 2a leads to poly(cyclooctene) and poly(cyclooctadiene) that have cis contents of >99%; all are previously unknown microstructures. Z-Selectivity is also observed in the metathesis of cis-4-octene and cis-3-hexene by initiator 2a to give cis-3-heptene.
Flook
Margaret M
MM
Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Jiang
Annie J
AJ
Schrock
Richard R
RR
Müller
Peter
P
Hoveyda
Amir H
AH
D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*
D000475:Alkenes; D009942:Organometallic Compounds; C542682:molybdenum hexaisopropylterphenoxide monopyrrolide; D008982:Molybdenum