Home About us Contact
|
Home About us Contact | ||
|
|
||
Cyclobutene Derivatives (cyclobutene + derivative)
Selected AbstractsChemInform Abstract: An Efficient One-Pot Synthesis of Trifluoromethyl-Substituted Cyclobutene Derivatives.CHEMINFORM, Issue 38 2010Mohmmad Hossein Mosslemin Abstract Cyclobutene derivatives (III) are obtained via intramolecular Wittig reaction between 1,1,1-trifluorobutane-2,4-diones and ethyl phenylpropiolate. [source] ChemInform Abstract: Cobalt Catalysis at the Crossroads: Cobalt-Catalyzed Alder,Ene Reaction versus [2 + 2] Cycloaddition.CHEMINFORM, Issue 32 2010Gerhard Hilt Abstract Depending on the Cobalt ligand used (dppp or dppe), cyclobutene derivatives [cf.(III)] or Alder-ene products [cf.(VIII)] arise with changing ratios, sometimes as a single product [cf.(V)]. [source] Intramolecular Reactions in Pseudo-Geminally Substituted [2.2]Paracyclophanes,CHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2007Lidija Bondarenko Dr. Abstract A selection of pseudo-geminally substituted [2.2]paracyclophanes, the alkynes 6, 7, 10, 11,a, and 11,b and the alkenes 8 and 9 were prepared for the study of intraannular reactions between functional groups in direct juxtaposition. Whereas 9 and 10 provide the corresponding cyclobutane and cyclobutene derivatives on irradiation (12 and 13, respectively), the bis-alkynes 7 and 11,b do not lead to a cyclobutadiene intermediate. In the latter case the "half-closed" butadiene derivative 17 was isolated. A Paterno,Büchi reaction took place on irradiation of 8 and 6, although the oxetene intermediate 21 produced in the second example did not survive the reaction conditions (ring-opening to 22). Bromine addition to 9, 10, and 7 occurred with high stereoselectivity (formation of the dibromides 27, 30, and 33, respectively), and is rationalized by postulating the formation of the cationic intermediates 26, 29, and 32, respectively. To study the interaction of a carbocation with a facing triple bond, the alcohol 34 was prepared from 6. On acid treatment ring closure to the triply-bridged phane 38 took place, accompanied by the hydration of the triple bond to the ketoalcohol 37. In an interesting intraannular [2+3]cycloaddition reaction the bis-acetylene 11,a, on treatment with n -butyl lithium, provided the cyclopentadiene derivative 42. That the two triple bonds of a pseudo-geminal diacetylene can engage in a cyclization reaction leading to the cyclopentadienone complex 44 was also shown by treating 11,b with iron pentacarbonyl. [source] Cyclobutenes as Isolable Intermediates in the Gold(I)-Catalysed Cycloisomerisation of 1,8-EnynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009Yann Odabachian Abstract The gold(I)-catalysed isomerisation of 1,8-enynes allows the efficient synthesis of functionalised bicyclo[5.2.0]nonenes. Notably, these cyclobutenes derivatives can be isolated as reactive intermediates that could undergo subsequent gold(I)-catalysed transformations such as isomerisation, fragmentation or ene reaction to furnish more structurally complex products. This study also provides useful information related to the mechanism leading to metathesis-type derivatives, examples of which were shown to be produced, in the present case, by a gold(I)-catalysed ring fragmentation of the cyclobutene moiety. [source] | ||||||||||