15918-08-8Relevant academic research and scientific papers
Preparation of Poly, (Pr2CCH2CH2CH2)n, via Regiospecific Ring Opening Polymerisation of 3,3-Dipropylcyclobutene
Alder, Roger W.,Allen, Paul R.,Khosravi, Ezat
, p. 1235 - 1236 (1994)
A general route to 3,3-disubstituted cyclobutenes is described and 3,3-dipropylcyclobutene is subjected to ring opening methathesis polymerisation (ROMP) using the Schrock initiator, Mo(=CHR)(=NAr)(OR')2, where R is C6H5C(Me)2-, Ar is 2,6-diisopropylphenyl and R' is (Me)3C- to give a polymer which is completely regiospecific (HT) and stereospecific (trans); the polymer is reduced to poly, which shows evidence of unusual properties associated with the conformational control exerted by the quaternary centres.
Synthesis and Structures of a Series of Bulky "Rind-Br" Based on a Rigid Fused-Ring s-Hydrindacene Skeleton
Matsuo, Tsukasa,Suzuki, Katsunori,Fukawa, Tomohide,Li, Baolin,Ito, Mikinao,Shoji, Yoshiaki,Otani, Takashi,Li, Liangchun,Kobayashi, Megumi,Hachiya, Makoto,Tahara, Yoshiyuki,Hashizume, Daisuke,Fukunaga, Takeo,Fukazawa, Aiko,Li, Yongming,Tsuji, Hayato,Tamao, Kohei
experimental part, p. 1178 - 1191 (2012/01/31)
A series of octa-R-substituted bromo-s-hydrindacenes, "Rind-Br," have been synthesized by a sequence of the Lewis acid catalyzed intramolecular FriedelCrafts reaction, bromination and vice versa. Their structural features and physical properties depend on
Conformational control by quaternary centres: theory, database evidence and application to polymers
Adler, Roger W.,Allen, Paul R.,Anderson, Kevin R.,Butts, Craig P.,Khosravi, Ezat,et al.
, p. 2083 - 2108 (2007/10/03)
The conformational effects of the quaternary centre in (RCH2CH2)4Xq species are studied by molecular mechanics calculations on hydrocarbons, ammonium ions, and related species, and the results verified by data on quaternary ammonium ions from the Cambridge Structural Database. Prn4C and Prn4N+ have just two low-energy structures, with D2d or S4 symmetry. All other conformations suffer from g+g- non-bonding interactions and will be populated to the extent of q-CH2 and the next set of torsions, -CH2-CH2-CH2-Xq, but the third set of torsions away from the quaternary centre is unaffected. Two competitive mechanisms for interconversion of the D2d and S4 conformations are proposed on the basis of molecular mechanics calculations. Polymers [(RCH2CH2)2C(CH2)2]n and [(RCH2CH2)2C(CH2)3]n are strain-free with controlled conformations for the -(CH2)2- and -(CH2)3- segments. In polymers containing simple alkyl side chains, there are two energetically similar conformations associated with the D2d local structure which have aaaa and ag+/-g+/-a torsion angle sequences for the polymer chain, and two comparable sequences ag+/-aa and ag+/-g+/-a associated with S4 local symmetry. Poly[(1,1-di-R)butane-1,4-diyl]s (R=Et,Pr,Bu and PhCH2CH2) have been prepared by ring opening metathesis polymerisation of 3,3-dialkylcyclobutenes, followed by diimide reduction, and their physical properties are in accord with these predictions. More highly structured side groups can act as extra conformational control elements, and the preparation of monomers and some polymers with these extra features is reported. Planar aromatic side groups like fluorene favour aaaa conformations, cyclohexyl side groups disfavour aaaa, but do not strongly discriminate between ag+/-aa and ag+/-g+/-a, adamantane side groups strongly favour ag+/-g+/-a, and a chiral ag+aa sequence is favoured for a polymer from (1R,2R,5R,7R)-2,8,8-trimethyltricyclo[5.1.1.02,5]non-3-ene, itself derived from α-pinene. Studies directed at preparing some structurally-related ketal polymers and a potential covalent ketal network are also described.
Formation of olefins upon oxidation of molybdenum alkyl carbynes. Organic radical reactivity in an organometallic radical cation
Schoch, Thomas K.,Orth, Stephen D.,Zerner, Michael C.,J?rgensen, Karl Anker,McElwee-White, Lisa
, p. 6475 - 6482 (2007/10/02)
Decomposition of the complexes (η5-C5H5)(CO){P(OMe) 3}Mo≡CR [R = C-C4H9, (CH2)3CH3, and CH(CH2-CH2CH3)2] in CHCl3 results in conversion of the carbyne ligand to a terminal olefin. The reaction is initiated by oxidation and occurs during photolysis in CHCl3 or upon slow diffusion of O2 into the reaction mixtures. Corroborating evidence for initiation of the reaction by electron transfer has been obtained by conversion of the butyl carbyne ligand of (η5-C5H5)(CO){P(OMe) 3}Mo≡C(CH2)3CH3 to 1-pentene upon electrochemical oxidation. Mechanistic studies were consistent with H-abstraction by the carbyne radical cation to yield a cationic carbene complex which forms the olefin in a H-shift process. INDO calculations on the carbyne radical cation [(η5-C5H5)(CO){P(OMe) 3}-Mo≡CCH2CH3]?+ indicate stabilization upon bending the Mo≡C-C angle from 180° to 120°. This change in geometry places spin density on the carbyne carbon in the radical cation although the initial oxidation occurs from an orbital that is primarily nonbonding metal d in character. The oxidized carbyne is thus able to function as a carbon-centered radical and abstract a hydrogen atom at the carbyne carbon. Although the olefin-forming reaction is general for alkyl carbynes with a hydrogen on C2, the tert-butyl carbyne (η5-C5H5)(CO){P(OMe) 3}Mo≡CC-(CH3)3 (2e) did not form an olefin upon oxidation. Instead, photolysis of 2e in CHCl3 yielded the dicnloromolybdenum carbyne (η5-C5H5)Cl2{P(OMe) 3}Mo≡CC(CH3)3 (5e) via a Cl-abstraction pathway.
PYROLYTIC FRAGMENTATION AND REARRANGEMENT OF 1-METHOXYCYCLOPROPYLAMINES
Kimpe, Norbert de,Buck, Kurt de,Booten, Karl
, p. 393 - 396 (2007/10/02)
N-Alkyl 2,2-dialkyl-1-methoxycyclopropylamines undergo a pyrolytic fragmentation into alkylisocyanides, methanol, 1,1-dialkylethylenes and novel α,β-unsaturated ketimines.Synthetic methods were developed for the generation of the latter 1-aza-1,3-dienes.
TRANSITION METAL ?-COMPLEXES IN ORGANIC SYNTHESIS 5. CROSS-COUPLING OF ORGANOMANGANESE COMPOUNDS WITH ALKENYL IODIDES
Kasatkin, A. N.,Romanova, T. Yu.,Tsypyshev, O. Yu.,Tolstikov, G. A.,Lomakina, S. I.
, p. 2410 - 2415 (2007/10/02)
Aryl organomanganese compounds ArMnX and Ph3MnLi (Ar = Ph, p-MeC6H4, p-MeOC6H4, p-ClC6H4, p-BrC6H4, α-naphthyl; X = Cl, Br) react with alkenyl iodides RR1C=CR2I (R = H, Pr, Bu, i-Bu, C6H13, CH2=CHCH2, Ph; R1 = H, Pr, C5H11; R2 = H, Pr, SiMe3) in THF at 0-20 deg C to give cross-coupling products RR1C=CR2Ar in high yields.
METHYLENECYCLOALKANES. STRAIN AND PROPERTIES
Kas'yan, L. I.,Seferova, M. F.,Gorb, L. G.,Kozina, M. P.,Dryuk, V. G.
, p. 1019 - 1025 (2007/10/02)
The synthesis of methylenecycloalkanes and of epoxides based on them was studied.The role of angular strain in the electron density distribution and the reactivity of the alkenes was investigated by quantum-chemical calculation by the LCAO-MO SCF method in the MINDO/3 valence approximation.The data from the calculation are compared with the spectral and kinetic parameters of the epoxidation of methylene-cycloalkanes by peracetic acid in ethyl acetate.
REACTION OF CYCLIC EPOXIDE COMPOUNDS WITH TRIPHENYLPHOSPHINE
Kas'yan, L. I.,Stepanova, N. V.,Galafeeva, M. F.,Boldeskul, I. E.,Trachevskii, V. V.,Zefirov, N. S.
, p. 109 - 112 (2007/10/02)
Significant differences were found in the reactivity of a series of epoxides of cycloalkenes and methylenecycloalkanes and diepoxides in reaction with triphenylphosphine, depending both on the steric effects of the cyclic fragments and on their strain.The level of the strain can be judged indirectly from the chemical shifts of the 1H and 13C nuclei and the spin-spin coupling constants of the C-H bonds in the epoxide ring.
A FACILE SYNTHESIS OF SYMMETRICAL 1,1-DISUBSTITUTED ETHYLENES
Larson, Gerald L.,Hernandez, David
, p. 1035 - 1038 (2007/10/02)
The reaction of ethyl trimethylsilylacetate with two equivalents of a Grignard reagent in ether followed by treatment with acid gives 1,1-disubstituted ethylenes in excellent yield.
