C鈥揌 Bond Activation Reactions in Ketones and Aldehydes Promoted by POP-Pincer Osmium and Ruthenium Complexes
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- 作者：Joaqu铆n Al贸s ; Miguel A. Esteruelas ; Montserrat Oliv谩n ; Enrique O帽ate ; Pim Puylaert
- 刊名：Organometallics
- 出版年：2015
- 出版时间：October 26, 2015
- 年：2015
- 卷：34
- 期：20
- 页码：4908-4921
- 全文大小：763K
- ISSN：1520-6041
文摘
The tetrahydride complex OsH4{xant(PiPr2)2} (1, xant(PiPr2)2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) activates an ortho-C鈥揌 bond of benzophenone and acetophenone to give the osmaisobenzofuran derivatives OsH{魏2-C,O-[C6H4C(R)O]}{xant(PiPr2)2} (R = Ph (2), CH3 (3)). The reaction of 1 with perdeuterated benzophenone leads to 2 partially protiated. The deuterium distribution in the latter suggests that the carbonyl group of the ketone traps the ortho-C鈥揌 addition product, which is the most disfavored from a kinetic point of view. The ruthenium counterpart RuH2(畏2-H2){xant(PiPr2)2}, generated in situ from the tetrahydrideborate RuH(畏2-H2BH2){xant(PiPr2)2} (4) and 2-propanol, also activates benzophenone and acetophenone to afford the ruthenaisobenzofurans RuH{魏2-C,O-[C6H4C(R)O]}{xant(PiPr2)2} (R = Ph (5), CH3 (6)). Both precursors favor the C鈥揌 bond activation over the C鈥揊 bond cleavage in fluorinated aromatic ketones. Thus, the fluorinated metalaisobenzofuran derivatives OsH{魏2-C,O-[C6H3FC(Me)O]}{xant(PiPr2)2} (7), OsH{魏2-C,O-[C6H4C(C6H3F2)O]}{xant(PiPr2)2} (8), and RuH{魏2-C,O-[C6H3FC(Me)O]}{xant(PiPr2)2} (9) have been obtained from the ortho-C鈥揌 bond activation of the corresponding substrates. Complex 1 also promotes the C尾鈥揌 bond activation of benzylidenacetone and methyl vinyl ketone to afford the osmafurans OsH{魏2-C,O-[C(R)CHC(Me)O]}{xant(PiPr2)2} (R = Ph (10), H (11)). The ruthenafuran counterparts RuH{魏2-C,O-[C(R)CHC(Me)O]}{xant(PiPr2)2} (R = Ph (12), H (13)) were similarly generated by using 4 in the presence of 2-propanol. The analogous reactions with benzylidenacetophenone yield mixtures of OsH{魏2-C,O-[C6H4C(CH鈺怌HPh)O]}{xant(PiPr2)2} (14) and OsH{魏2-C,O-[C(Ph)CHC(Ph)O]}{xant(PiPr2)2} (15) and RuH{魏2-C,O-[C6H4C(CH鈺怌HPh)O]}{xant(PiPr2)2} (16) and RuH{魏2-C,O-[C(Ph)CHC(Ph)O]}{xant(PiPr2)2} (17). While the formation of the osmaisobenzofuran 14 is slightly favored with regard to that of 15, no preference is observed for ruthenium. In contrast, both precursors favor OC鈥揌 activation over the cleavage of an ortho-C鈥揌 bond in aromatic aldehydes. Thus, their reactions with benzaldehyde yield MH(Ph)(CO){xant(PiPr2)2} (M = Os (18), Ru (19)). The decarbonylation of the substrate is also observed with 伪,尾-unsaturated aldehydes. Thus, the reaction of 1 with 1-cyclohexene-1-carboxaldehyde gives OsH(C6H9)(CO){xant(PiPr2)2} (20). Decarbonylation and dehydrogenation of the aldehyde to form the trans-dihydride OsH2(CO){xant(PiPr2)2} (21) take place with cyclohexane carboxaldehyde.