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Made significant additions. Eugene Kwan 04:46, 23 October 2005 (UTC)
Nice to see someone else has a probelm with selective monoprotection of symmetrical diols! I have tried the sodium hydride/TBSCl/THF procedure on 1,5-pentanediol, and got little better than statistical yields of mono product. I now usually employ a forcing excess of the (relatively cheap) diol (~4 eq), and use 1 eq. TBSCl in dichloromethane/2 eq. imidazole. works well for me, but i'll try the BuLi procedure and see what happens. thanks to whoever donated that piece of wisdom, its amazing what you'll find in wikipedia. Xcomradex 04:56, 15 June 2006 (UTC)
I've never tried the dichloromethane, but it's probably fine for an unhindered alcohol. I don't really find DMF to be a problem. I just extract under slightly acidic, then neutral conditions. It takes no more than 15 minutes, even on large scale. I guess DMF is pretty toxic, though. I've personally tried the BuLi procedure on 2-methyl-1,3-propanediol and it works great. It's lore from the Evans and Jacobsen labs here at Harvard. I also tried the NaH method, and got a horrible mixture. Eugene Kwan 00:44, 16 June 2006 (UTC)
Dichloromethane works fine for me, but i am typically protecting primary alcohols. DMF is ok to work with, once you get it dry, but DCM is easier imo. Tried your BuLi method on 1,5-pentandiol, was much better than the NaH method, and less wasteful than the excess method, and gave 85% yield of mono-product. Fantastic. Xcomradex 01:01, 19 June 2006 (UTC)