Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: bhkuk on March 21, 2008, 02:21:20 AM

Title: synthesis of D-erythrose derivatives- need your help
Post by: bhkuk on March 21, 2008, 02:21:20 AM

 

i want to synthesise S(R)-1-Deoxy-1-(p-tolylsulfinyl)-2-O-(benzyl)-3,4-O-isopropylidene-D-erythritol and i have question on the procedure so i will give details about it:
1. to asolution of S(R)-1-Deoxy-1-(p-tolylsulfinyl)-3,4-O-isopropylidene-D-erythritol in THF asuspension of NaH in THF is add at room temperature and the mixture should stirred at reflux for 30 minutes.
2. after cooling to room temperature i should add Tetrabutyl ammonium iodide and benzyl bromide and i should mix the reaction for 20 hours.
3. after it the solvent remove under reduced pressure  and the residue treats with aqueous sodiumbicarbonate and extracted with dichloromethane
4. the combine organic extracts were drying by sodium sulfate and the solvent was removed under reduced pressure and the residue was purified by flash chromatography.
so my question is:
1.why should i add NaH?
2. why should i add Tetrabutyl ammonium iodide what is the mechnism to its  reaction? and why should i mix the reaction for such long time (20 hours!!)
3. why using THF as solvent?
4. why should i purify it by flash chromatography?

Title: Re: synthesis of D-erythrose derivatives- need your help
Post by: AWK on March 21, 2008, 03:33:33 AM

1. Base that activates OH group
2. catalyst, some reactions needs even more time
3. Using NaH you have rather limited range of solvents
4. Do you prefer not purified compound?