[jayashae]

actually for the chloropropane, i can do sn2 attack with an OH group and then use jones for the -COOH then into acid chloride and that would be set.

as for the butyne, I can reduce it to a butene, then I'm not sure how to further it

[nox]

Butyne: you can pretty much do the exact same thing you did with the chloroproane (convert it to the acid chloride ultimately). If you start with an oxymercuration step that would get you to 2-butanone. From there it's just 2 steps to the acid chloride.

[jayashae]

hmm, didn't learn the oxymercuration.  but I can reduce the alkyne to an alkene through lindlar.  then from the alkene do permanganate to form the COOH, then acid chloride and same steps.

would ths work?

[jayashae]

wait but even if i do get those 2 products, one product can't meta-direct an acylation because the beneze would be too deactivated...

[nox]

oh right totally missed the part about you wanting to make propylbenzene first

well, you need a meta director, which means you can't really get rid of the C=O group (yet), so keep it there after you do the FC acylation with propionic chloride, then brominate the aromatic to put a Br in the meta position

I'm not going to walk you through everything but suffice to say, you can form the last C-C bond via a Grignard reaction from the brominated aromatic and an aldehyde that could be derived from butyne

[buRnINGbeND]

you guys are making this way too complicated.

first, do NOT do an oxymercuration of the alkyne.  this will give you a ketone, effectively making your butyne worthless.

you should instead do a hydroboration so you get butanal, which you can easily convert to an acid chloride by oxidixing with chromic acid and then treatment with SOCl₂.

do a FCA with your new acid chloride and you'll have a meta directing, 4 carbon containing chain.

do a FCA with your chloropropane and you'll have your molecule with the carbonyl still in it, which can be easily gotten rid of by a wolff-kishner reduction.

[nox]

^actually it would take exactly the same number of steps had an oxymercuration been performed -- from 2-butanone you do a haloform reaction to get the carboxylic acid (granted probably not a great reaction), which would then get converted to the acid chloride

the issue with the route you suggested, is that FC acylations on deactivated aromatics tend not to work so great, which is where the roundabout synthesis came from. otherwise yes that would be the most straightforward way to do it

[buRnINGbeND]

you can't do a haloform on MEK because then your resulting acid only has 3 carbons and you're still stuck with how to add a 4 carbon chain to the benzene ring, which is why you have to use an anti-markovnikov addition of water to the triple bond.

but people are talking about converting chloropropane to an acid chloride which is completely unnecessary, adding a halogen to the phenyl ring to direct a specific way which is completely unnecessary, and trying to add a o,p-directing substituent first, which is just going backwards.  we obviously need a m-directing substituent, and yes, even though you're deactivating your phenyl ring, it's better than killing your yield by going through 9.3784 steps to get to a product that isn't correct anyway.

[nox]

yes you're right about the butyne, my bad

the whole point about the chloroproane is to convert into into an m directing substituent

the problem with doing a straight FC alkylation with chloropropane after putting on the butanal fragment is that you will most certainly get the rearranged product (isopropyl) as the major isomer rather than the desired n-propyl chain, there's just no way around this and it'll end up being very messy.

[Dan]

the problem with doing a straight FC alkylation with chloropropane after putting on the butanal fragment is that you will most certainly get the rearranged product (isopropyl) as the major isomer rather than the desired n-propyl chain, there's just no way around this and it'll end up being very messy.

Agreed. The most reliable-looking route I can see is to make propionyl chloride, F-C acylation, brominate, Sonogashira, reduce, reduce. I think it's 8 steps total.

[buRnINGbeND]

sure you're going to get some rearrangement, but this is also something coming out of an ochem 2 text, so...

but if you really want to do it that way, you should be iodinating, not brominating, and you only need one reduction step.

[Dan]

sure you're going to get some rearrangement

I was taught is was mostly rearrangement rather than some rearrangement, but I may be mistaken.

but if you really want to do it that way, you should be iodinating, not brominating, and you only need one reduction step.

Why iodination? There is a large amount of literature addressing Sonogashira coupling with aryl bromides (and chlorides), which are easier to make than iodides.

What did you have in mind for the one step reduction?

[orgopete]

This is an interesting problem in that several functional group transformations are required for the overall transformation and the constant, predict the reactions for a class we did not attend. It looks as though a Sonogashira may have been discussed as a butyne is one of the starting materials, but 1-chloropropane was the other.

As the poster suggested, chloride to alcohol to acid to acid chloride to propiophenone is a plausible route.

This would be a route from there, and assuming Sonogashira was not covered.

Propiophenone to m-bromopropiophenone, Clemmensen reduction, magnesium to Grignard reagent.
Butyne + disiamylborane then NaOH/H2O2 to butyraldehyde. Add Grignard reagent to butyraldehyde and a catalytic hydrogenolysis or a second Clemmensen reduction.

[PhDoc]

Sometimes simplicity is best. This looks like an undergraduate problem on the benzene and aromaticity chapters. Metal-catalyzed cross couplings would not have been covered at this point in the course.

Convert the [1] alkyne to an aldehyde via hydroboration-oxidation, [2] oxidize the aldehyde with Jones reagent, [3] convert to the acid chloride, then do the [4] Friedel-Crafts. The second step is a simple [5] Friedel-Crafts alkylation. Finally, finish it off with [6] a Clemenson Reduction.

When a prof looks at most of the problems in an undergraduate organic chemistry textbook, TONS of flaws can be spotted. There's always the possibility for rearrangements, especially with Friedel-Crafts. Most textbooks still give the primary attachment as the major product.

Check Vollhardt & Schore, Streitwieser & Heathcock.

[buRnINGbeND]

well would you look at that.