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DOI: 10.1055/s-2006-955574
Synthesis of Cyclic Amidines via Ru-Catalyzed Hydroamination
S. Chang*, M. Lee, D. Y. Jung, E. J. Yoo, S. H. Cho, S. K. Han
Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
Publikationsverlauf
Publikationsdatum:
22. November 2006 (online)
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Significance
A Ru-catalyzed synthesis of cyclic amidines by the tandem reaction of aminoalkynes and tosylazides is reported. Ru(0,III), Pd(II), Pt(II), Au(III) and Cu(I) catalyze this reaction, among which, Ru3(CO)12 demonstrates high efficiency. This reaction tolerates the presence of a variety of electron-withdrawing groups R1. Interestingly, when n = 1, A is the major product, while B is preferentially formed when n = 2. Because the exo-methylene pyrrolidine is more stable than its endo-isomer, the former reacts less readily than its endo counterpart. A mechanism is postulated involving pathway A and pathway B routes to amidines which is supported by the fact that treatment of 1-benzyl-2-methylenepyrrolidine with TsN3 under the same reaction conditions results in the formation of a mixture of the same amidines. Furthermore, in a D-labeled experiment (the nitrogen and terminal alkyne were labeled), D-incorporation was observed at both migrated Me and C3 of the piperidine ring. Finally, the evolution of CH2N2 was demonstrated by a trapping experiment with PhCO2H.