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Synfacts 2011(6): 0603-0603
DOI: 10.1055/s-0030-1260450
DOI: 10.1055/s-0030-1260450
Synthesis of Heterocycles
© Georg Thieme Verlag
Stuttgart ˙ New York
A Boronic Acid Catalyzed Route to Imidazoles. Synthesis of LFA-1 Antagonists
R. P. Frutos*, T. Tampone, J. A. Mulder, Y. Xu, D. Reeves, X.-J. Wang, L. Zhang, D. Krishnamurthy, C. H. Senanayake
Boehringer-Ingelheim Pharma-ceuticals, Ridgefield, USA
Further Information
Publication History
Publication Date:
19 May 2011 (online)
Significance
Reported is the synthesis of 1H-imidazo[1,2-a]imidazole-2-ones 2 via the boronic acid catalyzed cyclodehydration of 1 in the presence of trimethylorthoformate. Investigation of this procedure demonstrated the necessity of the acetal functionality present in 1 for effective product formation. Furthermore, bulkier acetals (such as diethyl acetal) proved less efficacious in the transformation. Control reactions conducted demonstrated that the cyclic urea 4 is not an intermediate in the reaction as it fails to progress to the desired product under the optimized conditions. In addition, the reaction is reported to be highly scalable (>1 kg), although only limited substrate scope was examined.