[Saura]

Well, so I have been trying to deprotect the N-attached Fmoc group by using piperidine in DMF. But its quite puzzling that the TLC of the starting material and the product shows almost negligible difference. So sometimes its very difficult to conclude the reaction.  Moreover, the product is not much soluble in may of the organic solvents (DCM, EtOAc, Chloroform, Diethyl ether, etc).

[Dan]

But its quite puzzling that the TLC of the starting material and the product shows almost negligible difference. So sometimes its very difficult to conclude the reaction.

What solvent combinations have you tried using for the eluent? Assuming you're on silica, I would try combinations of: EtOAc/alkane, acetone/toluene, MeOH/DCM to start with. These systems can give surprisingly different separations.

Moreover, the product is not much soluble in may of the organic solvents (DCM, EtOAc, Chloroform, Diethyl ether, etc).

Could you simply run the reaction in one of these solvents and filter off the product at the end? It sounds like crystallisation (or trituration) would be the easiest method of purification given the chromatographic issues.

[Honclbrif]

Fmoc is a pretty big block of grease, so I would expect its presence/absence to substantially alter the Rf of most molecules (Except for the very large, or very hydrophobic). Another advantage of Fmoc is that it glows sky blue under long wave UV. If you don't see a fluorescent blue spot at the top of your plate after deprotection, then the deprotection probably failed.

[Saura]

Thank you Dan...

I got it today. I washed the product with ether and then filtered. Then I took a NMR in CDCl3 by sonicating the pinch of compound for a long time. The NMR confirmed the deprotection. I think the ether trituration is the key step. It removes most of the flourene derivative...I was worried about the TLC spot of the reaction which hardly showed varying Rf of the starting and end product.

By the way, Honclbrif mentioned a valid point. I was indeed getting a fluorescent active spot in the product TLC.