Rh(II)-Catalyzed Transannulation of 1,2,3-Triazoles with Nitriles

Content Provider	Scilit
Copyright Year	2008
Description	Reported is the efficient two-step synthesis of N-sulfonylimidazoles 5 starting from alkynes 1, sulfonyl azides 2 and nitriles 4. The formation of the required 1,2,3-triazole intermediates 3 was achieved under Cu(I) catalysis using conditions recently developed by the authors (J. Org. Chem. 2008, 73, 5520). Treatment of 3 with Rh(II) complexes generates the ring-opened rhodium α-iminocarbenoid which, upon reaction with nitriles 4, gives imidazoles 5 in modest to excellent yield. A range of catalysts and conditions were screened, and two sets of conditions were identified under both microwave and conventional heating. The scope of the reaction was well studied and tolerates alkyl, alkenyl and aryl nitriles. The nature of the C-4 substituent also has a significant effect on the reaction, with aromatic groups preferred over aliphatic groups. The two-step reaction was further telescoped into a one-pot process in one instance. Removal of the sulfonyl group from imidazoles 5 is easily achieved on treatment with HOBt.
Related Links	http://www.thieme-connect.de/products/ejournals/pdf/10.1055/s-0028-1087472.pdf
Ending Page	0027
Page Count	1
Starting Page	0027
ISSN	18611958
e-ISSN	1861194X
DOI	10.1055/s-0028-1087472
Journal	Synfacts
Issue Number	01
Volume Number	2009
Language	English
Publisher	Georg Thieme Verlag KG
Publisher Date	2008-12-18
Access Restriction	Open
Subject Keyword	Journal: Synfacts Organic Chemistry Em Class Two Step
Content Type	Text
Resource Type	Article