876938-53-3Relevant articles and documents
The value of 2JP–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stabilised phosphonium ylides
Aitken, R. Alan,Boubalouta, Youcef,Chang, Da,Cleghorn, Lee P.,Gray, Ian P.,Karodia, Nazira,Reid, Euan J.,Slawin, Alexandra M.Z.
, p. 6275 - 6285 (2017/09/29)
A survey of 20 carbonyl-stabilised phosphonium ylides with recently reported X-ray structures shows a strong correlation between the C[dbnd]P to C[dbnd]O torsion angle and the value of 2JP–CO, with high values being associated with an anti configuration and low with syn. Seven new X-ray structural determinations are reported, several for types of ylide not crystallographically characterised before, and these also conform to this pattern. The value of 2JP–CO is then correlated with whether or not thermal extrusion of Ph3PO occurs to give alkynes for over 200 ylides and an empirical rule developed that the extrusion never occurs for ylides where this value is > 11 Hz. This is used to rationalise the anomalous behaviour of some trioxo ylides and cyclic ylides, two of which afford cycloalkynes, isolated after rearrangement as the isomeric 1,3-dienes. The rule also holds for a family of novel highly fluorinated ylides which afford fluorinated alkynes in good yield upon flash vacuum pyrolysis.
Reducing characteristics of borohydride exchange resin-CuSO4 in methanol
Sim, Tae Bo,Yoon, Nung Min
, p. 1101 - 1107 (2007/10/03)
Reducing characteristics of borohydride exchange resin (BER)-CuSO 4 (cat.) were studied in methanol at room temperature. Carbon-carbon double bonds conjugated with benzene or carbonyl group were more rapidly reduced than was the case with isolated double bonds. Carbonyl groups were readily reduced, whereas esters and amides were inert, and nitriles were slowly reduced. High chemoselectivity was also observed in halide reductions: p-bromochlorobenzene and p-bromoiodobenzene were reduced quantitatively to chlorobenzene and bromobenzene, respectively. Aliphatic epoxides were inert to this reagent; however, styrene oxide derivatives were readily reduced to the corresponding deoxygenated products. Aliphatic azides were reduced slowly during 6 h, whereas phenyl azide was transformed to aniline in 1 h. Nitrocyclohexane was reduced at room temperature, but nitrobenzene, nitrosobenzene, azobenzene, and azoxybenzene required an elevated temperature (65 °C) for rapid reductions (1 h). Similarly, N,N-dimethylanihne N-oxide was reduced at room temperature, whereas pyridine N-oxide required refluxing. Finally, among the sulfur compounds tested, only diphenyl disulfide was reduced readily, and sulfide, aliphatic disulfide, sulfoxide, sulfone, and tosylate were inert to this reducing system.
Photoinduced Reactions of Cr(CO)3-Coordinated 1,3,5-Cycloheptatriene Cycloaddition with an Alkyne and Catalytic 1,6-Hydrogenation
Fischler, Ingrid,Grevels, Friedrich-Wilhelm,Leitich, Johannes,Oezkar, Saim
, p. 2857 - 2862 (2007/10/02)
Irradiation of Cr(CO)3(η6-1,3,5-cycloheptatriene) (1) in the presence of bis(trimethylsilyl)ethyne results in cycloaddition of the alkyne to the cycloheptatriene ligand, yielding Cr(CO)3(η4:2-7,8-bis(trimethylsilyl)bicyclonona-2,4,7-triene) (2, 60percent yield, Π = 0.08), which upon oxidative decomposition with Ce(IV) releases the organic cycloadduct, 7,8-bis(trimethylsilyl)bicyclo-nona-2,4,7-triene (3).Photocatalytic hydrogenation of 1,3,5-cycloheptatriene in the presence of complex 1 affords 1,3-cycloheptatriene.This process involves 1,6-addition of hydrogen, as demonstrated by using D2.Key Words: Chromium complexes/ Cycloheptatriene, hydrogenation of/ Photoreactions/ Photocatalysis/ Alkynes, cycloadditon with
