A convenient route to six-membered heterocyclic carbene complexes: Reactions of aminoallenylidene complexes with 1,3-bidentate nucleophiles |
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Affiliation: | 3. Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, Texas 75708;4. the Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905, and;5. Center for Research on Environmental Disease and Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky 40536;1. Department of Pharmaceutical Science and Technology, College of Chemistry and Biology, Donghua University, Shanghai 201600, PR China;2. Janssen Pharmaceutica, API Development, Turnhoutseweg 30, 2340 Beerse, Belgium;3. STA Pharmaceuticals, 288 Fute Zhong Rd, Shanghai 200131, PR China;1. Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain;2. Institute of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Beethovenstrasse 55, 38106 Braunschweig, Germany;3. Institut de Tècniques Energètiques i Centre de Recerca en NanoEnginyeria, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain;1. Department of Chemistry, Faculty of Science, University of Zanjan, 45371-38791, Zanjan, Iran;2. Fakultät für Chemie und Pharmazie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, Haus D, D-81377 München, Germany;3. Department of Chemistry, Shahid Beheshti University, G. C., Evin, Tehran 1983963113, Iran |
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Abstract: | Pentacarbonyl dimethylamino(methoxy)allenylidene complexes of chromium and tungsten, [(CO)5M C C C(NMe2)OMe] (M = Cr (1a), W (1b)), react with 1,3-bidentate nucleophiles such as amidines and guanidine, H2N–C( NH)R (R = Ph, C6H4NH2-4, C6H4NO2-3, NH2), by displacing the methoxy substituent to give exclusively dimethylamino(imino)-allenylidene complexes, [(CO)5M C C C{N C(NH2)R}NMe2] (2a–5a, 2b). Treatment of the chromium complexes 2a–5a with catalytic amounts of hydrochloric acid or HBF4 gives rise to an intramolecular cyclization. Addition of the terminal NH2 substituent to the Cα–Cβ bond of the allenylidene chain affords pyrimidinylidene complexes 6–9 in high yield. In contrast to the chromium complexes 2a–5a, the corresponding tungsten complex 2b could not be induced to cyclize due to the lower electrophilicity of the α-carbon atom in 2b. The dimethylamino(phenyl)allenylidene complex [(CO)5Cr C C C(NMe2)Ph] (10) reacts with benzamidine or guanidine similarly to 1a. However, the second reaction step – cyclization to give pyrimidinylidene complexes – proceeds much faster. Therefore, the formation of an imino(phenyl)allenylidene complex as an intermediate is established only by IR spectroscopy. The analogous reaction of 10 with 3-amino-5-methylpyrazole affords, via a formal [3+3]-cycloaddition, a pyrazolo[1,5a]pyrimidinylidene complex 13. Compound 13 is obtained as two isomers differing in the relative position of the N-bound proton (1H or 4H). The related reaction of 10 with thioacetamide yields a thiazinylidene complex and additionally an alkenyl(amino)carbene complex. |
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