Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: rapilch on May 08, 2011, 09:23:39 AM
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Does anyone what is occurring here? Im not sure how to show arrow pushing/intermediates.
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Given the starting materials and the products, I am doubtful of the first step, except for the acid. Then it looks like formation of a bromoimidate, cyclization, and tautomerization.
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My attempt:
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi5.photobucket.com%2Falbums%2Fy153%2FDemocAnarchis%2Fmechanism.png&hash=4924a832c42dbbcc1f57d7209ebfd965851789a5)
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What you have drawn is somewhat reasonable. I doubt a chloride would add to a carboxylic acid, but I understand you are trying to make an acid chloride. Since the starting material is also listed as the ester, I didn't know formation of the acid chloride was necessary and I did not expect that PCl5 would convert that ester to its acid chloride. I am not saying it couldn't, but it isn't high on my list of probable reactions. If one heated the heck out of it, then okay.
I am skeptical of the cyclization of the nitrile with the acid chloride. I prefer to simply proton the nitrile and add bromide to it to form a bromo imidate. Now the nitrogen is sp2 and I think better aligned to add to a C=O group, either an ester or an acid chloride (if I understand the question correctly).
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Ok so I am presuming the the methyl groups off the carbonyl in the middle of the reaction are chlorine atoms?
Also I do not see and Ester anywhere? Am I ignorant? I do see two carboxylic groups, which surely can be converted to acyl chlorides with PCl5...?
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Structure 8, E = COOMe
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. ahh the read the original post shutdown procedure... sorry about that.