From: frances rees (fsr8g$##$virginia.edu)
Date: Mon Jan 08 2001 - 10:03:33 EST
I was wondering if anyone has suggestions for the synthesis of
2-ethynyl-oxirane. I have tried several different literature methods,
however, I have had no luck (probably in part because of my limited
experience). I have tried to use commercially prepared
chloroacetaldehyde after crystallizing the material out of water,
drying, and then the suggested Grignard with ethynyl magnesium bromide,
but was only able to recover starting materials. I thought it was
possible to use the tetrahydrothiophene synthesis ( reference listed
below) starting with propargyl bromide since I am not interested in the
functionalities introduced in the original French paper.... I still
think this is the most feasible method of the two, however, I have
tried this method several times with no luck. However, I do not think
I created the ylide properly, ( I allowed the temperature of the
reaction to get too high). To this end I would appreciate any
suggestions for carrying out the synthesis using this reaction;
(Propargyl Bromide + tetrahydrothiophene to make the salt, then
formation of the ylide with NaOH and introduction of formaldehyde to
form 2-ethynyl-oxirane (thus recovering the tetrahydrothiophene),
temperature control, sequence; i.e. does the ylide formation with NaOH
need to be in a separate step from the introduction of formaldehyde to
actually form the final compound?. L. Brandsma ("Preparative Acetylenic
Chemistry", second edition, Elsevier, New York, 1988, page 266) lists a
synthesis for the compound using a lithium reagent, however, here you
would still need to synthesize chloroacetaldehyde, which takes me back
to my original problem. At any rate I have found that 2-ethynyl-oxirane
is used quite frequently in synthesis procedures, and I am hoping
someone may know of a better way, or have suggestions. The references
for the reactions listed on Beilstein are : R. Lespieau, Bull. Soc.
Chim. France [4] 43, 199 (1928); or for the tetrahydrothiophene
method, Beny, Jean-Pierre et al, BSCFAS, Bull. Soc. Chem. Fr., 2, 9-10,
1981...There are actually two articles here, 369-376 for the first part
of the synthesis and pages 377-386 for the final part. I thank you for
your time!!!!!!!!!!
Frances Rees
fsr8g$##$virginia.edu
__________________
ORGLIST - Organic Chemistry Mailing List
Website / Archive / FAQ: http://www.orglist.net/
List coordinator: Joao Aires de Sousa (jas$##$mail.fct.unl.pt)
This archive was generated by hypermail 2.1.4 : Fri Sep 19 2003 - 12:16:27 EDT