Re: Carbazole substitution on dichloroacetone


"Uncle Al" <UncleAl0@xxxxxxxxxxxxx> wrote in message
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lucasea@xxxxxxxxxxxxx wrote:

"Uncle Al" <UncleAl0@xxxxxxxxxxxxx> wrote in message
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lucasea@xxxxxxxxxxxxx wrote:

The desired product is the carbazole aminal of (HC=O)-(C=O)-CH3.

Interesting synthetic suggestions, Al. However, did I miss something? I
was thinking 1,3-dichloroacetone--that's the isomer I've used in the
past,
and I didn't even know 1,1-dichloroacetone was easy to get until I just
looked at my Aldrich catalog. How did you come to the conclusion that he
wants to make the 1,1-dicarbazole?

The answers he gets are only as good as the question he asks. Why
would anybody have a problem making the 1,3-isomer?

I hadn't thought about problems with haloform-type reactivity of the
1,1-dichloro, although 1,3-dichloroacetone has got to be pretty acidic too.
As far as I recall, 1,3-dichloroketones convert to cyclopropenones under
rather mild conditions.

It's not even clear to me that it's possible to methylate carbazole with
MeI, under either neutral or basic conditions. It's a really crappy
nucleophile. Good suggestions for conditions, though. I hate HMPA
(toxicity) and DMF (involatility), but they are good conditions of last
resort.

Eric Lucas


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