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An Efficient Procedure for the Synthesis of Crystalline Aryldiazonium Trifluoroacetates – Synthetic Applications
Author(s) -
Colas Christophe,
Goeldner Maurice
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199906)1999:6<1357::aid-ejoc1357>3.0.co;2-p
Subject(s) - chemistry , deprotonation , aniline , tetrafluoroborate , diazonium compounds , anhydrous , yield (engineering) , azo coupling , protonation , substituent , chemical shift , organic chemistry , inorganic chemistry , catalysis , ionic liquid , ion , materials science , metallurgy
We have developed a very mild procedure for the synthesis of crystalline aryldiazonium trifluoroacetate salts in high yields under anhydrous conditions. Over thirty mono‐ or polyfunctional aniline derivatives have been diazotized by this method, including water‐ and acid‐sensitive substrates. The o ‐ and p ‐hydroxyaryldiazonium salts, derived from the corresponding anilines, could be deprotonated by treatment with K 2 CO 3 to yield pure diazoquinones. NMR and UV/Vis spectra have been recorded for all the synthesized salts; the data are in good agreement with the rather limited published data and constitute a first extensive report of 13 C‐NMR chemical shifts in diazonium salts. An excellent linear relationship emerged between Brown's substituent constants s + p and the 13 C ipso chemical shifts. The diazonium salts obtained proved to be much more soluble in organic solvents than their tetrafluoroborate counterparts. They were tested in Pd‐mediated coupling reactions of various Carbon‐Carbon double bonds, and were found to give good yields within short reaction times under very mild conditions. We believe that diazonium trifluoroacetates represent a very attractive alternative to diazonium tetrafluoroborates.