Ring-Opening of a Cyclic Imine:  The First Step of Imine ROMP

Cantrell, Gidget K.; Geib, Steven J.; Meyer, Tara Y.

doi:10.1021/om990522r

Cited by 19 publications

(15 citation statements)

References 9 publications

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“…The Mo−N(1) distance of 1.7348(18) Å is consistent with a metal−nitrogen triple bond, 2c,d,3f, and the Mo−N(2) and N(3) amide distances are within the range expected for Mo−N single bonds . The Mo−O(1) distance of 1.9344(15) Å and the Mo−C(19) distance of 2.209(2) Å are both consistent with metal−atom single bonds .…”

Section: Resultssupporting

confidence: 56%

Synthesis and Reactivity of Molybdenum(IV) Olefin Complexes Supported by a Chelating Ancillary Ligand

et al. 2001

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The reactivity of [Mo(NPh)Cl 2 (o-(Me 3 SiN) 2 C 6 H 4 ‚THF)] (1) with β-hydrogen-containing Grignard reagents was examined. Reaction of 1 with 2 equiv of RMgCl (R ) CH 2 CH 2 Ph, CH 2 CH 2 CH 3 , CH 2 CH(CH 3 ) 2 , CH 2 CH 2 CH 2 CH 3 , and CH(CH 3 )CH 2 CH 3 ) gave Mo(IV) olefin complexes of the type [Mo(NPh)(η 2 -olefin)(o-(Me 3 SiN) 2 C 6 H 4 )] (olefin ) styrene (2a), propene (2b), isobutene (2c), 1-butene (2d), and 2-butene (2e)). The crystal structure of 2a is reported. Reaction of 1 with 2 equiv of ethylmagnesium chloride afforded a mixture of metallacyclopentane [Mo(NPh)(CH 2 CH 2 CH 2 CH 2 )(o-(Me 3 SiN) 2 C 6 H 4 )] (3a) and an oligomeric molybdenum species having the empirical formula [Mo(NPh)(o-(Me 3 SiN) 2 C 6 H 4 )] x (3b). Pure 3a was obtained by reaction of 1 with 2 equiv of EtMgCl under an atmosphere of ethylene. Treatment of 3a with excess PMe 3 in benzene at 80 °C afforded [Mo(NPh)(η 2 -ethylene)(o-(Me 3 SiN) 2 C 6 H 4 )-(PMe 3 ) 2 ] (3c). Compounds 2c and 2a react with acetone to yield the oxametalacyclopentanes [(Mo(NPh)(C(CH 3 ) 2 CH 2 C(CH 3 ) 2 O)(o-(Me 3 SiN) 2 C 6 H 4 )] (4a) and [(Mo(NPh)(C(H)PhCH 2 C-(CH 3 ) 2 O)(o-(Me 3 SiN) 2 C 6 H 4 )] (4b), respectively. An X-ray crystallographic study on a single crystal of 4a was performed. Only one diasteriomer of 4b was formed and isolated. Its structure was assigned by NMR spectroscopy (ghmbc, ghmqc, and NOESY).

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Section: Resultssupporting

confidence: 56%

Synthesis and Reactivity of Molybdenum(IV) Olefin Complexes Supported by a Chelating Ancillary Ligand

et al. 2001

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“…The ring-opening metathesis of pyrroline presented herein represents an important milestone in our effort to generalize ring-opening metathesis polymerization (ROMP) to heteroolefinic substrates. Previously, we − and others have studied metathesis activity of acyclic imine substrates with metal alkylidene and metal imide functional groups, but only recently did we observe the first ring-opening of a cyclic heteroolefin substrate . In this paper we describe in detail the ring-opening of pyrroline by olefin metathesis complexes of the general formula Mo(CHR‘)(NAr)(OR) 2 .…”

Section: Introductionmentioning

confidence: 87%

Ring-Opening Metathesis of a Cyclic Imine

2000

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Pyrroline, a five-membered cyclic imine, undergoes ring-opening metathesis with alkylidene complexes of the class Mo(CHR‘)(NAr)(OR)2 (Ar = 2,6 diisopropylphenyl; R = CMe3, CMe2(CF3), CMe(CF3)2; R‘ = CMe3, CPhMe2). An intermediate pyrroline-bound complex was isolated and characterized crystallographically for the R = CMe2(CF3) derivative. This adduct, Mo(CHBut)(NAr)[OCMe2(CF3)]2[pyrroline], transforms to the mixed bis(imide) product, Mo(NCH2CH2CH2CHCHBut)(NAr)[OMe2(CF3)]2, with a first-order rate constant of 1.4 × 10-2 min-1 at 55 °C. The reaction of the R = CMe3 derivative produces not only the ring-opened product but also a byproduct, Mo[CH(CMe2Ph)(C4H8N)](O)(NAr)(OBut).

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“…In contrast to imido alkylidenes of molybdenum not containing the tether, on replacement of the triflates in 4 by hexafluoro- tert -butoxide (OBu t F6 ) using TlOBu t F6 we were unable to isolate a stable product. However, TlOBu t F6 triflate metathesis (Scheme ) in the presence of quinuclidine (quin) provides isolable Mo(OBu t F6 ) 2 (quin)(N-2,4-Pr i 2 C 6 H 2 -6-CH 2 CH 2 CMe 2 CH) ( 5 ) …”

Section: Resultsmentioning

confidence: 99%

Synthesis, Properties, and Structure of Tethered Molybdenum Alkylidenes

2008

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A new class of molybdenum alkylidenes has been prepared where the alkylidene is tethered to an imido ancillary ligand. The amine required for the synthesis is accessible in 38% yield in five steps from 1,3-diisopropylbenzene. The amine is then installed to generate the tethered alkylidene bis(triflate) complex, which was structurally characterized as its DME adduct. The triflates are replaced by hexafluoro-tertbutoxide groups using the thallium salt of the alkoxide, and the bis(alkoxide) was characterized as its quinuclidine adduct. For comparison, an alkylidene bis(alkoxide) was prepared without the tether and having a formula similar to that of the tethered system. The structures from X-ray diffraction and NMR spectroscopy of the two complexes with and without the tether but with similar formulas are compared. The tether has the apparent effect, judging from J CH couplings in the alkylidene and angles in the solidstate structure, of reducing the strength of the R-agostic interaction. Four complexes were structurally characterized during this study: 4-Pr i 2 C 6 H 2 -2-CH 2 CH 2 CMe 2 CHd](DME)(OTf) 2 , Mo(OBu t F6 ) 2 (quin)-[dN-2,4-Pr i 2 C 6 H 2 -2-CH 2 CH 2 CMe 2 CHd], Mo[N(2,4-Pr i 2 -6-MeC 6 H 2 )] 2 (neopentyl) 2 , and Mo(OBu t F6 ) 2 (quin)-[N(2,4-Pr i 2 -6-MeC 6 H 2 )][dC(H)Bu t ].

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Ring-Opening of a Cyclic Imine: The First Step of Imine ROMP

Cited by 19 publications

References 9 publications

Synthesis and Reactivity of Molybdenum(IV) Olefin Complexes Supported by a Chelating Ancillary Ligand

Synthesis and Reactivity of Molybdenum(IV) Olefin Complexes Supported by a Chelating Ancillary Ligand

Ring-Opening Metathesis of a Cyclic Imine

Synthesis, Properties, and Structure of Tethered Molybdenum Alkylidenes

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