[Fern]

I have a retrosynthesis problem, and I have two places for reaction.  One is a reaction on a secondary carbon pulling a hydrogen off doing an E2 and making a Br leave off of a tertiary carbon.  The second option is reacting on a primary carbon doing an SN2 and making an I leave.  I was using an organometallic reagent of Li-CH=CH2.  I made the reaction take place in DMSO and the reaction occur at a colder temperature.  Will this ensure that the organometallic reagent will do the SN2 not the E2?

Any help and explanation would be useful!!

[Dan]

Draw please.

Alkyl lithium reagents are extremely basic though, and it is unlikely that you can suppress elimination reactions - in practice they are rarely used for aliphatic substitution reactions for this reason.

I've seen milder organometallic reagents used (hint), but I suspect there is a better disconnection - so please attach a diagram.

[Fern]

I'm really sorry about the mess on the page.. just ignore the stick notes.. The problem is on the top of the page, and what I tried to do is everything else on the white