1,721,037 research outputs found
(Z)— and (E)—1,2—Bis(phenylsulfonyl)ethylenes as Synthetic Equivalents to Acetylene as Dienophiles
No full textA new method for introducing an ethylenic bridge via a cycloaddition reaction has been developed. It makes use of either (Z)- or (E)-1,2-bis(phenylsulfonyl)ethylene (5 or 6) as synthetic equivalents of acetylene. The high activation due to the two sulfonyl groups promotes cycloadditioti even to very unreactive dienes. The removal of the two sulfonyl groups for the required formation of the carbon-carbon double bond is promoted by reduction with metal amalgams in high yields. These properties, associated with the stability of the reagents and the ease of performance of the reactions, make this method a very useful synthetic tool for the preparation of polycyclic dienes and a valid alternative to the commonly available reagents that largely depend upon oxidative methods. © 1984, American Chemical Society. All rights reserved
An Improved Synthesis of 7,8-Bis(methylene)-bicyclo(2.2.2)octa-2,5-diene
No full texta cheaper and more expeditious synthesis of 7,8-dimethyl-bis(methylene)-bicyclo[2.2.2]octa-2,5-diene is reporte
Dichotomy in the Double Bond Reactivity of 2,3-Bis(phenylsulphonyl)bicyclo-(2.2.1)hepta-2,5-diene and Related Compounds
No full textSelectivity between the two double bonds of the title compound was observed for a number of reagents. For example, cycloaddition with cyclopentadiene and anthracene, as well as reduction with molecular hydrogen (uder Pd catalysis), took place at the unsubstitued double bond, while cyclohexadiene and alfa terpinene gave (uncatalyzed) reduction at the more substituted double bond
Structure of 3,4-bis(phenylthio)cyclobutene-1,2-dione
No full textthe lack of reactivity of 3,4-bis(phenylthio)cyclobutene-1,2-dione as a dienophiles can be rationalized in terms of steric hindrance at the CC(1)-C(2) double bon
1,2-bis(phenylsulfonyl)alkenes as versatile groups in organic synthesis: The preparation of alkyl- and aryl-substituted norbornadienes via the Diels-Alder cycloaddition - Grignard reaction - desulfonylation sequence
No full texta synthetic methodology for the preparation of the formal Diels-Alder cycloadducts of alkyl- and ary-substituted acetylenes which exemplifies the utility of bis(phenylsulfonyl)alkenes in organic synthesis is presented
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