19057-51-3

Upstream product

• 2789-88-0 1,2-bis(4-methylphenyl)acetylene 
• 1133438-04-6 (di-2-pyridylmethyl-amide)₂Fe 

Relevant academic research and scientific papers

Nickel-Catalyzed Facile [2+2+2] Cyclotrimerization of Unactivated Internal Alkynes to Polysubstituted Benzenes

A catalytic [2+2+2] cyclotrimerization of unactivated internal alkynes providing cyclotrimerization products in excellent yields with high regioselectivity is described. The transformation is accomplished by using a simple catalytic mixture comprising Ni(acac)2, an imidazolium salt and a Grignard reagent at room temperature or 60 °C for 20 min or 1 h.

C-C bond formation and related reactions at the CNC backbone in (smif)FeX (smif = 1,3-di-(2-pyridyl)-2-azaallyl): Dimerizations, 3 + 2 cyclization, and nucleophilic attack; Transfer hydrogenations and alkyne trimerization (X = N(TMS)2, dpma = (Di-(2-pyridyl-methyl)-amide))

Molecular orbital analysis depicts the CNCnb backbone of the smif (1,3-di-(2-pyridyl)-2-azaallyl) ligand as having singlet diradical and/or ionic character where electrophilic or nucleophilic attack is plausible. Reversible dimerization of (smif)Fe{N(SiMe3)2} (1) to [{(Me3Si)2N}Fe]2(μ-κ3, κ3-N,py2-smif,smif) (2) may be construed as diradical coupling. A proton transfer within the backbone-methylated, and o-pyridine-methylated smif of putative (bMe2 oMe2smif)FeN(SiMe3)2 (8) provides a route to [{(Me3Si)2N}Fe]2(μ- κ4,κ4-N,py2,C-(bMe, bCH2,oMe2(smif)H))2 (9). A 3 + 2 cyclization of ditolyl-acetylene occurs with 1, leading to the dimer [{2,5-di(pyridin-2-yl)-3,4-di-(p-tolyl-2,5-dihydropyrrol-1-ide)}FeN(SiMe 3)2]2 (11), and the collateral discovery of alkyne cyclotrimerization led to a brief study that identified Fe(N(SiMe 3)2(THF) as an effective catalyst. Nucleophilic attack by (smif)2Fe (13) on tBuNCO and (2,6-iPr 2C6H3)NCO afforded (RNHCO-smif)2Fe (14a, R = tBu; 14b, 2,6-iPrC6H3). Calculations suggested that (dpma)2Fe (15) would favorably lose dihydrogen to afford (smif)2Fe (13). H2-transfer to alkynes, olefins, imines, PhNNPh, and ketones was explored, but only stoichiometric reactions were affected. Some physical properties of the compounds were examined, and X-ray structural studies on several dinuclear species were conducted.

Palladium-catalyzed cycloisomerizations of diarylacetylenes: Synthesis, structures, and physical properties of highly substituted naphthalenes and 8,8 a-dihydrocyclopenta[a]indenes

Depending on the electronic properties of their substituents, the major products generated by palladium-catalyzed cycloisomerizations of diarylalkynes are either highly substituted 8,8a-dihydrocyclopenta[a]indenes 3 or naphthalenes 4. The structures of these compounds were verified by X-ray crystallographic analysis. Many functional groups tolerated the reaction conditions evaluated in this study. The isotope-labeled experiments indicated that added water has a critical role in forming both classes of compounds. The photophysical and electrochemical properties of cycloadducts 3 and their analogues were systematically studied and compared with computational predictions based on density functional theory. Dihydrocyclopenta[a]indenes 3 in either solid or liquid form display strong luminescence, whereas cyclopenta[a]indene 11 j is practically nonfluorescent. The functional groups directly attached to the backbone of compound 3 significantly influenced physical properties. The steric effect arising from the aryl substituents caused different luminescence phenomena, including aggregation-induced and -enhanced emission. Copyright

Synthesis, structure, and photophysical properties of highly substituted 8,8a-dihydrocyclopenta[a]indenes

(Chemical Equation Presented) A triple round: A palladium-catalyzed cyclotrimerization of 1,2-diarylacetylenes has been developed to synthesize highly substituted 8,8a-dihydrocyclopenta[a]indenes. One such cycloadduct (1) displays unusual aggregation-induced emission with a strong blue fluorescence (see picture). The structures of the products have been confirmed by X-ray crystal analysis.

A deuterium labelling study into the insertion of diphenylacetylenes into iron-aryl bonds

The mechanism of the reaction of dicarbonyl(η5-cyclopentadienyl)phenyliron, 1, with diphenylacetylene to give 2,3-diphenyl--inden-1-one has been investigated using a partially deuterated 1.The mechanistic pathway of the reaction is discussed in terms of the labelling of the indenones obtained.The reaction of phenylacetylene with 1 gives a mixture of products including 2,4,6-triphenyl-4'-methylbenzophenone and C-4,C-6a-dihydro-4-(4'-methylphenyl)-2-phenylpentalene(1-r-3aH)one.

CYCLOTRIMERIZATION OF SUBSTITUTED ACETYLENES TO ARENES BY TITANIUM COMPLEXES

Cyclotrimerization experiments of substituted acetylenes to arenes with (a) C8H8Ti complexes and with (b) TiCl3 are reported.A cyclotrimerization mechanism is proposed which involves the concerted trimerization of three acetylenes coordinated to a divalent titanium centre.The organometallic compounds isolated from the reaction mixtures, viz. (C8H8TiPhC2Ph)2, C8H8TiC4Ph4 in (a) and - + in (b) are shown not be intermediates in the cyclotrimerization.