Or, as a trivial name, cis-benzylideneacetone.
It is widely known that a simple aldol condensation between acetone and benzaldehyde will yield 4-phenylbut-3-en-2-one, which would easily be reduced
to form the alcohol.
However, a very significant part will go all the way to dibenzylideneacetone and, furthermore, the vast majority of the benzylideneacetone formed is,
in fact, the trans (E) isomer.
To overcome this, I have thought about reacting sodium phenylacetylide (synthesis here) with acetaldehyde (if not readily available, prepare by reacting ethanol with PCC).
The resulting compound, 4-phenyleth-3-yn-2-ol can be reduced with Lindlar catalyst to form (3Z)-4-phenyleth-3-en-2-ol, which unfortunately comes out
as a racemate.
Oxidation of this alcohol would yield the cis-enone, probably useful if Diels-Alder like reactions are desired or Michael addition ones.
The good aspect is that it is easily made from fairly OTC reagents*, as well as providing a nice ground to prepare more exciting compounds (the enone
is a great dienophile, but apart from Diels-Alder, many other syntheses can be attempted).
* As long as you can get some Lindlar, I guess. CuReUS - 26-4-2016 at 03:22
Quote:
However, a very significant part will go all the way to dibenzylideneacetone
what if the benzaldehyde was slowly dripped into a flask with an excess of acetone ? I have read somewhere that there is a trick to control these type
of reactions.Instead of using benzaldehyde directly,convert it into its bisulphite salt and then use it.
I had two other ideas to get the cis-enone
1. why don't you react benzaldehyde with the lithium enolate(using LDA) or silyl enol ether of acetone(mukaiyama aldol addition) to get the
b-hydroxyketone.Then you could use a special dehydrating agent(don't ask me what) which will dehydrate to give only the cis-enone
