From: by way of (stefan.berger$##$reseachem.ch)
Date: Tue Jun 29 1999 - 03:26:57 EDT
We have to synthetis 2-cyanoethyl-N,N-Diisopropylphosphoramidochloridite
in our lab for some studies.
The literatur to this synthesis is well known (for example:
J.chem.soc.perkin Trans 1, 1993, 43) but in the final step we always
have a decomposition of the produkt (formation of DIPA) and so we are
not able to use the produkt. We think we have tried everything to avoid
decomposition (destillation under Ar, dry N2, high vakkum) but we always
got this decomposition.
The way we are doing the synthesis is the following:
First step:
3-Hydroxypropionitril and 1,1,1,3,3,3-hexamethyldisilazane were heated
under reflux conditions. Then a solution uf this in dry acetonitril was
added to a solution of PCl3 in dry acetonitril at aprox. -50=B0C.
Work-up by destillation. The quality of this product is good (>95% by
1H-NMR)
Second step:
A solution of the product out of the first step in dry ether was added
to a solution of DIPA in dry ether at -20=B0C. Stirring over night and
allowed to warm up slowly to room temperature. After 20h the products
were filtered and the filtrate was concentrated under reduced pressure.
Vakuum distillation should then give our desired product. Insted we got
decomposition. We tried this reaction x-times with the same result.
Does anybody have a better methode for this synthesis or any ideas what
we are doing wrong. Is there a special thing to know? Slowly we are
getting mad about it.
Thanks for any help in advance
Steven
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Stefan Berger
ReseaChem GmbH
Chemical Research Laboratory
Pestalozzistrasse 16
3400 Burgdorf
Switzerland
Tel. ++ 41 (0) 34 424 03 10
Fax. ++ 41 (0) 34 424 03 12
E-Mail: stefan.berger$##$reseachem.ch
Internet: http://www.reseachem.ch
ReseaChem GmbH:
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