764-35-2Relevant academic research and scientific papers
ON THE REACTION OF METALLATED ACETYLENES AND ALLENES WITH CARBON DISULFIDE. INFLUENCE OF THE ALKALI METAL COUNTER-ION AND THE SUBSTITUENTS IN THE ACETYLENE AND ALLENE ON THE COURSE OF THE REACTION
Jong, R. L. P. De,Brandsma, L.
, p. 277 - 282 (1986)
Addition at low temperatures of carbon disulfide to a solution of the lithium compound (R1 = CH3, C3H7, Ph, OCH3, SCH3) results in the initial formation of an allenic carbodithioate H2C=C=C(R1)CSSLi, while for R1 = t-C4H9 or SiMe3 acetylenic carbodithioates R1CCCH2CSSLi are formed.The initial products undergo very rapid subsequent reactions.For R1 = CH3 or C3H7 the lithium compound adds (in the allenic form) in a conjugated fashion to the C=C-C=S system of the allenic carbodithioate.The acetylenic dithioates are deprotonated to give the geminal dithiolates R1CC-CH=C(SLi)2.For R1 = Ph, OCH3 or SCH3, subsequent deprotonation at the terminal carbon atom of the initial allenic dithioate gives enyne dithiolates HCC-C(R1)=C(SCH3)2; this reaction proceeds more satisfactorily with the potassium compounds.
Propargylic C(sp3)-H Bond Activation for Preparing η3-Propargyl/Allenyl Complexes of Yttrium
Nagae, Haruki,Kundu, Abhinanda,Tsurugi, Hayato,Mashima, Kazushi
, p. 3061 - 3067 (2017/09/05)
Propargylic C(sp3) - H bond activation of 1-substituted-1-propynes, such as 1-trimethylsilyl-1-propyne, 2-hexyne, and 1-phenyl-1-propyne, was achieved by treatment with an alkylyttrium complex 8 bearing an ene-diamido ligand to give the corresponding (η3-propargyl/allenyl)yttrium complexes 7a-c. A unique delocalized η3-propargyl/allenyl structure of these three complexes was revealed by NMR spectroscopy and X-ray single crystal analyses. To elucidate the reactivity of the η3-propargyl/allenyl unit of complexes 7a-c, we conducted two reactions with N-methylaniline and N,N′-dicyclohexylcarbodiimine. For protonation by N-methylaniline, we found that the product distribution of monosubstituted internal alkynes and allenes depended on the substituent on the η3-propargyl/allenyl moiety: 7a and 7b afforded the corresponding internal alkynes as the major products, whereas the major protonation product of 7c was phenylallene. For the insertion of N,N′-dicyclohexylcarbodiimine, complex 7a selectively yielded η3-{N,N′-dicyclohexyl-2-(3-trimethylsilylpropargyl)amidinate}yttrium 12a, while complex 7c produced η3-{N,N′-dicyclohexyl-2-(1-phenylallenyl)amidinate}yttrium complex 13c, though complex 7b gave a mixture of η3-{N,N′-dicyclohexyl-2-(3-normalpropylpropargyl)amidinate}yttrium complex 12b and η3-{N,N′-dicyclohexyl-2-(1-normalpropylallenyl)amidinate}yttrium 13b in an 83:17 ratio. On the basis of the product distributions in these two-types of reactions, (η3-propargyl/allenyl)yttrium complexes were shifted into preferentially favorable η1-allenyl species or η1-propargyl species depending on the substituents prior to the reaction with electrophiles via a four-membered cyclic mechanism.
Polylithiumorganic compounds. Part 28. The reaction of allene and alkyl substituted allenes with lithium metal
Maercker, Adalbert,Tatai, Andrea,Grebe, Burkhard,Girreser, Ulrich
, p. 1 - 8 (2007/10/03)
The reaction of allene (3a) and alkyl substituted allenes 1,2-hexadiene (3b), cyclopropylallene (3c), and vinylidene cyclopropane (3d) with lithium metal was investigated in order to access 2,3-dilithioalkenes 4a-d. These dilithioalkenes 4a-d are very reactive in polar solvents like THF and act as strong bases, either metalation of the starting allene 3a-d, the solvent, or sufficiently acidic intermediates like 8 a-d is observed. The metalation products 5-7 show follow-up reactions like 1,3-H shift to the corresponding 1-lithio-1-alkynes 8 and subsequent metalation to the dilithioalkynes 9. Additionally, lithium hydride elimination and ring-chain rearrangement (for 5c) are observed. 1,2-Hexadiene (3b) can be brought to reaction with lithium metal in the apolar solvent pentane, here the follow-up reactions are much slower due to the insolubility of 4b. In all cases the elucidation of the reaction pathways is hampered by the formation of complex mixtures of, amongst others, regio- and stereoisomeric products upon quenching with simple electrophiles.
Dehydrogenative silylation of terminal alkynes catalyzed by Ytterbium- imine complexes
Takaki, Ken,Kurioka, Masanobu,Kamata, Tohru,Takehira, Katsuomi,Makioka, Yoshikazu,Fujiwara, Yuzo
, p. 9265 - 9269 (2007/10/03)
Catalytic dehydrogenative silylation of terminal alkynes with hydrosilanes has been achieved by using divalent Yb-imine complexes. The reaction with mono-, di-, and trihydrosilanes gave the corresponding alkynylsilanes in good yields. α,ω-Diynes were similarly silylated at both termini. Thus, oligomers were obtained from the diynes and dihydrosilanes. In addition, it has been found that the imine complexes exhibit catalytic activity for redistribution of the silyl groups of the alkynylsilanes and for Si-Si bond fission of disilanes.
Isomerization of terminal alkynes catalyzed by itterbium(II)-aromatic imine complexes
Makioka, Yoshikazu,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo,Saiki, Akira,Takaki, Ken
, p. 349 - 356 (2007/10/03)
Ytterbium-aromatic imine dianion complexes 2, which can easily be prepared from metallic ytterbium and aromatic imines 1, can act as effective catalysts for the isomerization of terminal alkynes 3 under mild conditions to afford internal alk-2-ynes 4 in good yields.In the reaction of 1-hexene 3a, 2-hexyne 3a, 2-hexyne 4a can be simply obtained by trap-to-trap distillation and the catalytic system can be reused for the isomerization of 3a without other treatments. - Keywords: lanthanoid-imine complex; terminal alkyne; isomerization; alk-2-yne
Ytterbium(II)-aromatic imine dianion complexes-catalyzed isomerization of terminal alkynes
Makioka, Yoshikazu,Saiki, Akira,Takaki, Ken,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo
, p. 27 - 28 (2007/10/03)
Ytterbium-aromatic imine dianion complexes, easily prepared from ytterbium metal and aromatic imines, can act as effective catalysts for the isomerization of terminal alkynes to afford internal alkynes in good to high yields.
Mn(I)-Induced 1,6-Demethanation across the CC Triple Bond of Linear Alkynes in the Gas Phase. A Case for the Generation of Manganese Cycloalkynes?
Schulze, Christian,Schwarz, Helmut
, p. 67 - 70 (2007/10/02)
Complexes of Mn(alkynes)+ were generated in the gas phase and found to exhibit a reactivity which is even richer than that of the analogous Fe(alkyne)+ species.Among the many unimolecular dissociations, the Mn+-induced demethanation of 4-octyne is of particular interest.The study of isotopomers and the effects of alkyl chain lengths reveals the operation of an unprecedented 1,6-elimination mode across the CC triple bond, and the experimental results may be explained by invoking the intermediate generation of the as yet unknown metallacycloalkynes.The implications of the unexpected, rich gas-phase ion chemistry of Mn+ with regard to theoretical models are discussed.
On 1.2-Shift Reactions and C-H-Insertions of Acyclic Alkylidene Carbenes
Ondruschka, Bernd,Remmler, Matthias,Zimmermann, Gerhard,Krueger, Christian
, p. 49 - 54 (2007/10/02)
Two series of acyclic terminal vinyl bromides (1...4 and 5...7) were tested in the reaction with potassium tert-butoxide as precursors of alkylidene carbenes.As expected 1 up to 4 only give 1-alkynes whereas the 2-methylated vinyl bromides 5, 6 and 7 yield 1-methylated cyclopentenes predominantly besides 2-alkynes.The formation of cyclopentenes indicates a reaction route via alkylidene carbenes and 1,5-C-H-insertion reactions, that of 2-alkynes is convincing evidence for 1,2-alkyl shift reactions in 2-methyl substituted alkylidene carbenes.The selectivity of 1,5-C-H-insertion depends on the degree of alkyl substitution of the C-5-atom.At 240 deg C the selectivity is 1deg:2deg:3deg ca. 1:54:240.
THE ELECTRON SPIN RESONANCE SPECTRA OF THE ANNULENE (CYCLOBUTADIENE) RADICAL CATIONS, R4C4+.
Courtneidge, John L.,Davies, Alwyn G.,Lusztyk, Ewa,Lusztyk, Janusz
, p. 155 - 164 (2007/10/02)
A series of simple (R=R') and mixed (RR') cyclobutadiene radical cations, R2R'2C4+., have been prepared by photolysis of the alkynes, RCCR' or of mixtures of the alkynes RCCR and R'CCR', in dichloromethane in the presence of aluminium chloride, and the e.s.r. spectra have been recorded.The magnitude of the 13C hyperfine coupling in Et4C4+. confirms that it is a ?-radical, with no evidence for out-of-plane or in-plane (Jahn-Teller) distortion.The values of a(Hβ) for the radicals (RCH2)4C4+. and (RCH2)2R'2C4+. indicate that, as the bulk of the alkyl substituents increases, the group R is pushed out of the plane of the ring.Some unusual temperature effects on a(Hβ) are ascribed to interaction of the radical cation with the solvent or with the counterion.As the bulk of the alkyl groups increases, the g-value decreases from 2.0030 to about 2.0022. cis- and trans-Isomers of the radicals Me2tBu2C4+., Et2tBu2C4+., iBu2tBu2C4+., and propably Me2Et2C4+. have been identified, and the spectra of cis- and trans-Me2tBu2C+. are analysed in terms of breaking of the degeneracy of the molecular orbitals of the cyclobutadiene system by differential electron release by the alkyl groups (tBu > Me).
DIRECT PHOTOLYSIS AT 185 nm OF 1-ALKENES IN SOLUTION. MOLECULAR ELIMINATION OF TERMINAL HYDROGENS
Inoue, Yoshihisa,Mukai, Toshio,Hakushi, Tadao
, p. 1725 - 1728 (2007/10/02)
Direct irradiations at 185 nm of 1-octene and 2-methyl-1-pentene in pentane gave alkylidene carbenes through the molecular elimination of terminal hydrogens, as well as double-bond migration products via 1,3-shift of allylic hydrogen and radical-derived products.
