[kims]

the lithium acetylide doesn't attack the carbonyl apparently so do its do conjugate addition?
help please

[venkatjohnny]

Hi,
lithium acetylide is a hard nucleophile , so it attacks mainly on hard electrophile like carbonyl centre(hard-hard interactions). To attack on alkene carbon u need to have a soft nucleophile. For example Gilman reagent is a soft nucleophile( R2CuLi), Cu makes the R group to be soft. That's why all the Gilman reagents will result in conjugate addition.
Better u refer ORGANIC CHEMISTRY by CLAYDEN for this orbital interaction topic..have a nice time

[kims]

i did the hard to hard in the carbonyl carbon but apparently this is the wrong product. so i was wondering what other possibilities there were. thanks

[sjb]

As I mentioned previously, I think Weinreb amides (the RNMeOMe species) react with organolithiums to form ketones.

So, after forming the alcohol (or more probably the alkoxide in this case, as I don't see any acid in your conditions), I think the tetrahedral intermediate collapses and kicks out ^-NMeOMe.

Initial product perhaps the keto-acetylene? I'm not sure how labile TMS is in your system, this may fall off?

S

[kims]

Is this what you are talking about?

[macman104]

Yes, that is what is meant.  Check this link for more info.