- 1,4-Dilithio-1,3-butadlenes
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On treatment with (trimethylstannyl)lithium in THF at -78°C, 1,4-dichlorobutadienes (4) gave the stereoisomeric 1,4-bis(trimethylstannyl)-1,3-butadienes (5-7). Compounds 5 and 7 may be converted to the corresponding 1,4-dilithio-1,3-butadienes (1 and 3) by treatment with excess methyllithium, while 6 and 7 may be converted to 1 by reaction with 1 equiv of methyllithium.
- Ashe III, Arthur J.,Mahmoud, Samir
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p. 1878 - 1880
(2008/10/08)
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- Stereochemistry of Dehydrogenation of 1,4-cyclohexadiene with 2,3-dichloro-5,6-dicyano-p-benzoquinone
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cis- and trans-(3,6-D2)-1,4-cyclohexadienes 1a and 1b have been synthesized from cis-3,4-dichlorocyclobutene (5).Aromatization to benzene with DDQ is cis-stereospecific with an uncertainty of 5percent.This results is discussed in relation to concerted or stepwise mechanisms for aromatization of 1,4-dihydroaromatics with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ).
- Mueller, Paul,Joly, Daniel,Mermoud, Francois
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p. 105 - 112
(2007/10/02)
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- Infrared multiphoton induced isomerization of cis-3,4-dichlorocyclobutene. I. Experimental results
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The yield and product distribution in the laser-induced isomerization of cis-3,4-dichlorocyclobutene (DCCB) have been measured as functions of laser fluence, DCCB pressure, and buffer gas pressure.Both Woodward-Hoffman allowed and "forbidden" isomers were observed.The fraction of "forbidden" products was found to increase linearly with fluence above a threshold of 3.5 J/cm2.At high fluence the yield increased quadratically with neat DCCB pressure.Both the yield and fraction of "forbidden" products declined monotonically with buffer gas pressure.These observations are explained in terms of a two-channel mechanism, in which the allowed isomer is formed in a concerted path and the forbidden isomers are produced from a diradical intermediate in a nonconcerted reaction.
- Presser, Nathan,Mao, Chung-Rei,Moriarty, Robert M.,Gordon, Robert J.
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p. 6021 - 6029
(2007/10/02)
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