[fishsticks]

Hey guys, I am having a real difficult time figuring this synthesis problem out. If someone could help me out that I would appreciate it greatly. Thanks

Question 1:

The only restriction is that the starred carbon in W must originate from the starred carbon in V

Question 2:


Thank you in advance.. The Fish Lover!

[RBF]

For #1, check out the malonic ester synthesis as a starting point.  Figure out what the alkyl halide must be to give you carbon skeleton you need. 

For #2,  check out Robinson annulation as a starting point.

[lutesium]

You are totally right RBF!!!         

1st RXN is not too hard to explain Firstly get a Ph-Cl and attach it to the malonic ester by the usage of a strong base such as NaOEt and then Chlorinate benzoic acid that has formed!!!
http://www.organic-chemistry.org/namedreactions/malonic-ester-synthesis.shtm

2nd RXN is a Robinson Annulation you can find the mechanism at http://www.organic-chemistry.org/namedreactions/robinson-annulation.shtm

[AWK]

You are totally right RBF!!!         

1st RXN is not too hard to explain Firstly get an Ph-Cl and attach it to the malonic ester by the usage of a strong base such as NaOEt

I doubt

1,5-dibromopentane will work in malonic synthesis

[lutesium]

1,5-dibromopentane will work in malonic synthesis

Where's 1,5-dibromopentane I can't see! If you've said BromoHexane I'd understand but where did 1,5-dibromoPentane come from???

[RBF]

You have to add 5 carbons to the methylene carbon of the malonic ester to complete the 6 membered ring.  The thought was that adding 1 equivalent of 1,5 dibromopentane to the malonate carbanion would form a C-C bond to one end of the dibromopentane.  Adding a second equivalent of base would regenerate another stabilized carbanion which would complete the ring by displacement of the other bromine.  Hydrolysis and decarboxylation would complete the synthesis.
A question was raised in a previous post whether this strategy would work.  Perhaps there are side reactions I have not anticipated.

[sjb]

1st RXN is not too hard to explain Firstly get a Ph-Cl and attach it to the malonic ester by the usage of a strong base such as NaOEt and then Chlorinate benzoic acid that has formed!!!
http://www.organic-chemistry.org/namedreactions/malonic-ester-synthesis.shtm

Minor point, but it's not benzoyl chloride you are looking at forming

edit: another thing is that typically benzenes will not react in the S_N1 / S_N2 fashion you need for malonate chemistry to work here. I think you can form 2-phenylmalonates using diethyl carbonate and esters of phenylacetic acid in a Claisen style reaction.

S

S

[lutesium]

Sorry for the mistake but I'd say cyclohexanoic acid! But in the malonic acid synthesis we can clearly see that hexyl halide can be attached to the malonic acid by means of a deprotonating reagent so why do we need 1,5-DibromoPentane???


Lutesium...

[lutesium]

Malonate Chemistry that sounds great!!! Another area to work on!!!


Lutesium...

[sjb]

..so why do we need 1,5-DibromoPentane???

One carbon of the to-be formed 6 membered ring is already in place, as the central carbon of the malonate. If you tried the chemistry with a alpha,omega disubstituted hexane you'd get a cyclohePTane as the product.

S