Alternative reaction pathways in domino reactions of hydrazinediidozirconium complexes with alkynes

• Verfasst von: Gehrmann, Thorsten [VerfasserIn]
• Verfasst von: Scholl, Solveig A. [VerfasserIn]
• Verfasst von: Lloret Fillol, Julio [VerfasserIn]
• Verfasst von: Wadepohl, Hubert [VerfasserIn]
• Verfasst von: Gade, Lutz H. [VerfasserIn]
• Titel: Alternative reaction pathways in domino reactions of hydrazinediidozirconium complexes with alkynes
• Titelzusatz: dedicated to Professor Walter Siebert on the occasion of his 75th birthday
• Verf.angabe: Thorsten Gehrmann, Solveig A. Scholl, Julio Lloret Fillol, Hubert Wadepohl, and Lutz H. Gade
• E-Jahr: 2012
• Jahr: 17 February 2012
• Umfang: 17 S.
• Fussnoten: Gesehen am 26.04.2018
• Titel Quelle: Enthalten in: Chemistry - a European journal
• Ort Quelle: Weinheim : Wiley-VCH, 1995
• Jahr Quelle: 2012
• Band/Heft Quelle: 18(2012), 13, Seite 3925-3941
• ISSN Quelle: 1521-3765
• DOI: doi:10.1002/chem.201103497
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: alkynes
• Sach-SW: CN coupling
• Sach-SW: domino reactions
• Sach-SW: indoles
• Sach-SW: zirconium
• K10plus-PPN: 1572392584

Abstract

Reaction of [Zr(NAr)2Npy(NMe2)2] (Ar=3,5-xylyl: 2 a, mesityl: 2 b) with one or two molar equivalents of 1,1-diphenylhydrazine gave the mixed amido/hydrazido(1−) complex [Zr(NMes)2Npy(HNNPh2)(NMe2)] (3), the bis-hydrazido complex [Zr(NMes)2Npy(HNNPh2)2] (4), and, in the presence of excess 4-dimethylaminopyridine (DMAP), hexacoordinate hydrazinediidozirconium complexes [Zr(NXyl)2Npy(NN(Me)Ph)(dmap)2] (5) and [Zr(NXyl)2Npy(NNPh2)(dmap)2] (6). The reaction of one equivalent of the zirconium-hydrazinediide [Zr(NTBS)2Npy(NNPh2)(py)] (1) with disubstituted alkynes at RT for 16 h led to the formation of seven-membered diazazirconacycles 7 a-7 e in high yields. Similar reactivity was observed by reacting bis-amido complex 2 b with one molar equivalent of the corresponding alkyne and diphenylhydrazine. The formation of the seven-membered zirconacycles implied a key coupling step that involved the alkyne and one of the aryl rings of the diphenylhydrazinediido ligand. In some cases, such as the reaction with 2-butyne, the corresponding metallacycle was only obtained in modest yields (45 % for the reaction with 2-butyne) and a second major product, vinylimido complex 9, was formed in almost equal amounts (42 %) by 1,2-amination (formal insertion of the alkyne). The formation of compounds 7 a and 9 followed in part the same sequence of reaction steps and a key intermediate, an azirinido complex, represented a “bifurcation point” in the reaction network. Reaction of 1.2 equivalents of several diarylhydrazines and various substituted alkynes (1 equiv) at ambient temperature (or at 80 °C) in the presence of 10 mol % [Zr(NXyl)2Npy(NMe2)2] (2 a) gave the corresponding indole derivatives. On the other hand, the replacement of 1,1-diarylhydrazines by 1-methyl-1-phenyl hydrazine led to head-to-head cis-1,3-enynes in good yields.