oh uh lemme do _Organic Syntheses_ roulette again
(among other things it's kinda calming)
and the number is 4263!
http://orgsyn.org/demo.aspx?prep=v94p0153
wow, ok...a curious reaction, synthesis of something that looks like a valuable synthetic intermediate even though it's only a few carbons long, allenylcarbinol. so H₂C=C=CH-CH₂OH. a more systematic name is 2,3-butadienol.
allenes are funny creatures!
synthesis involves refluxing propargyl alcohol, HC≡C-CH₂OH, with paraformaldehyde (that's the insoluble polymeric form of formaldehyde, much nicer to handle than formalin), diisopropylamine, copper(I) iodide as a catalyst, in tetrahydrofuran. well!
presumably the diisopropylamine is a sufficiently strong base to strip the acetylenic hydrogen on the propargyl alcohol, which then coordinates with the copper(I). then this acetylide attacks formaldehyde (formed in situ from the paraformaldehyde)
and finally water gets eliminated and you get the allene. or something like that. I'm trying to do that in my head instead of writing it down (it's good practice for me!)
well, fun! the _Organic Syntheses_ article then goes on to show a whole bunch of reactions that allenylcarbinol has been used in.
one to file away for who-knows-when.
