Osmium-Acyl Decarbonylation Promoted by Tp-Mediated Allenylidene Abstraction: A New Role of the Tp Ligand
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https://figshare.com/articles/dataset/Osmium_Acyl_Decarbonylation_Promoted_by_Tp_Mediated_Allenylidene_Abstraction_A_New_Role_of_the_Tp_Ligand/2266927
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资源简介：
Phenylacetylene
and 1,1-diphenyl-2-propyn-1-ol displace the pyridyl
and ethylene ligands of OsTp{κ1-C[NC5H3Me]}(η2-CH2CH2)(PiPr3) (1) to afford the alkynyl-vinylidene derivatives OsTp(CCR)(CCHR)(PiPr3) (Tp = hydridotris(pyrazolyl)borate; R = Ph,
(2), C(OH)Ph2 (3)). Stirring
of toluene solutions of 3 in the presence of neutral
aluminum oxide initially produces the dehydration of the vinylidene
ligand to give the alkynyl-allenylidene OsTp{CCC(OH)Ph2}(CCCPh2)(PiPr3) (4), which subsequently undergoes a
Meyer-Schuster rearrangement to yield the acyl-allenylidene OsTp{C(O)CHCPh2}(CCCPh2)(PiPr3) (5). In toluene, at 60 °C, the
B–H bond of the Tp ligand of 5 abstracts the allene
from the osmium coordination sphere by means of a 1,1-hydroboration
of the Os–Cα double bond. As a result, the
acyl decarbonylation takes place to form Os(Ph2CCCHTp)(CHCPh2)(CO)(PiPr3) (6). In acetonitrile at 60 °C, the allene tautomerizes
into the alkyne to afford Os(Ph2HCCCTp)(CHCPh2)(CO)(PiPr3) (7). The abstraction
modifies the reactivity of the system toward HBF4. Thus,
while the protonation of 5 leads to the alkylidyne [OsTp{C(O)CHCPh2}(CCHCPh2)(PiPr3)]BF4 (8), the protonation of 6 and 7 gives the alkylidenes [Os(Ph2CCCHTp)(CHCHPh2)(CO)(PiPr3)]BF4 (9) and [Os(Ph2HCCCTp)(CHCHPh2)(CO)(PiPr3)]BF4 (10). Both 9 and 10 are unstable in solution.
In dichloromethane, at room temperature, they evolve into the corresponding
olefin derivatives [Os(Ph2CCCHTp)(η2-CH2CPh2)(CO)(PiPr3)]BF4 (11) and [Os(Ph2HCCCTp)(η2-CH2CPh2)(CO)(PiPr3)]BF4 (12) by means
of a Cβ,Cα-hydrogen shift on the
alkylidene ligand.
创建时间：
2016-02-17
