1007-52-9Relevant academic research and scientific papers
Palladium-catalyzed and organozinc-promoted synthesis of dienes from allylic esters possessing an acyloxy or alkoxy group
Hattori, Hatsuhiko,Katsukawa, Masahiro,Kobayashi, Yuichi
, p. 5871 - 5875 (2007/10/03)
Organozinc and a Pd catalyst promoted formation of dienes from allylic esters possessing a leaving group such as acyloxy and alkoxy groups next to the allyl moiety. The reaction proceeded with high regio- and stereoselectivity when applied to secondary allylic substrates.
Substituent effect on the competition between hetero-Diels-Alder and cheletropic additions of sulfur dioxide to 1-substituted buta-1,3-dienes
Roversi, Elena,Monnat, Frederic,Vogel, Pierre,Schenk, Kurt,Roversi, Pietro
, p. 733 - 760 (2007/10/03)
The reactivity of sulfur dioxide toward variously substituted butadienes was explored in an effort to define the factors affecting the competition between the hetero-Diels-Alder and cheletropic additions. At low temperature (2 in the hetero-Diels-Alder mode in the presence of CF3COOH as promoter. In the case of (E)-1-ethylidene-2-methylidenecyclohexane ((E)-4a), the [4+2] cycloaddition of SO2 is fast at -90° without acid catalyst. (E)-1-(Acyloxy)buta-1,3-dienes (E)-1c, (E)-1y, and (E)-1z with AcO, BzO, and naphthalene-2-(carbonyloxy). substituents, respectively also undergo the hetero-Diels-Alder addition with SO2+CF3COOH at low temperatures, giving a 1:10 mixture of the corresponding cis- and trans-6-(acyloxy)sultines c-2c,y,z and t-2c,y,z, respectively). Above -50°, the sultines undergo complete cycloreversion to the corresponding dienes and SO2, which that add in the cheletropic mode at higher temperature to give the corresponding 2-substituted sulfolenes (=2,5-dihydrothiophene 1,1-dioxides) 3. The hetero-Diels-Alder additions of SO2 follow the Alder endo rule, giving first the 6-substituted cis-sultines that equilibrate then with the more stable trans-isomers. This statement is based on the assumption that the S=O group in the sultine prefers a pseudo-axial rather than a pseudo-equatorial position, as predicted by quantum calculations. The most striking observation is that electron-rich dienes such as 1-cyclopropyl-, 1-phenyl-, 1-(4-methoxyphenyl)-, 1-(trimethylsilyl)-, 1-phenoxy-, 1-(4-chlorophenoxy)-, 1-(4-methoxyphenoxy)-, 1-(4-nitrophenoxy)-, 1-(naphthalen-2-yloxy)-, 1-(methylthio)-, 1-(phenylthio)-, 1-[(4-chlorophenyl)thio]-, 1-[(4-methoxyphenyl)thio]-, 1-[(4-nitrophenyl)thio]-, and 1-(phenylseleno)buta-1,3-diene, as well as 1-(methoxymethylidene)-2-methylidenecyclohexane (4f) do not equilibrate with the corresponding sultines between -100 and -10°, in the presence of a large excess of SO2, with or without acidic promoter. The hetero-Diels-Alder additions of SO2 to 1-substituted (E)-buta-1,3-dienes are highly regioselective, giving exclusively the corresponding 6-substituted sultines. The 1-substituted (Z)-buta-1,3-dienes do not undergo the hetero-Diels-Alder additions with sulfur dioxide.
Catalytic palladium-mediated bisdiene carbocyclizations: Bisdiene to enediene cycloisomerizations
Takacs, James M.,Clement, Francis,Zhu, Jingyang,Chandramouli, Sithamalli V.,Gong, Xiaoping
, p. 5804 - 5817 (2007/10/03)
The palladium-catalyzed cycloisomerization of acyclic bisdienes to cyclized enedienes defines a novel strategy for the stereoselective cyclization of certain unsymmetric bisdiene substrates to form functionalized five-and six-membered rings. The full deta
Rh(I)-katalysierte Cycloaromatisierung acyclischer 3-En-1,5-diine
Ohe, Kouichi,Kojima, Masa-aki,Yonehara, Koji,Uemura, Sakae
, p. 1959 - 1962 (2007/10/03)
Keywords: Cycloaromatisierungen; Endiine; Katalyse; Rhodiumverbindungen
REDUCTION OF ALLYLIC ACETATES BY USING A NOVEL Pd(O)-SmI2 SYSTEM
Tabuchi, Takanori,Inanaga, Junji,Yamaguchi, Masaru
, p. 601 - 602 (2007/10/02)
Allylic acetates were reduced to alkenes in high yields with SmI2 and 2-propanol in the presence of a catalytic amount of palladium(O) complex.
