[acetone]

hi guys.

i stucked in my reaction. The starting material was added with meldrum acid and DMAP under N2 at 0 degree celcius (see attachment).Then dropwise of EDC was added for 15 minutes. the rxn was left for room temperature for 4 hours.The crude mixture was extracted with cold EtOAc,cold 5% citric acid, cold water and finally brine.It was dried over sodium sulphate and concentrated.This stage how i obtained the intermediate pdt.

Then it was refluxed for 10 minutes in EtOAc, and according to journal it should give the final pdt.

From the NMR, the peak was similar for the intermediate and final pdt.So it seemed to me the reflux did not transform the intermediate to the final pdt. The cyclised cmpd can be obtained directly from the stage (a).

The final product (the cyclised) is really hard to form. from the silica TLC it was polar (Petroleum ether 2/EtOAc 3/1 drop acetic acid). Is it any possibilities to optimise the formation of final pdt? Is the technique need to be modified or i was unaware of something? do give me some advices.

[Doc Oc]

I love how people make carbamate reactions look so easy.  They're not (I say this as someone that battled a Cbz-amine cyclization for quite a while and lost).  I'm willing to bet you will need significantly more reflux time or possibly another condition altogether.  It's not clear to me how you will facilitate that cyclization, let alone the decomposition of the Meldrum's acid without some acid to open it.

[acetone]

I've forgotten to mention that TLC showed there was a meldrum's acid left in the reaction mixture of stage (a).meldrum's acid itself did'not react completely .