155890-75-8Relevant academic research and scientific papers
Niobium(III)-induced reductive coupling of benchrotrenic aldehydes and ketones
Szymoniak, Jan,Luque, Lionel,Besancon, Jack,Moise, Claude
, p. 89 - 94 (2007/10/02)
The (arene)tricarbonylchromium(benchrotrenic)oxo compounds BctCOR (Bct = Cr(CO)3C6H5; R = H, alkyl or aryl) undergo a reductive coupling reaction with NbCl3(DME), leading to the mono- and bis-metallated alkenes, Bct(R)C=C(R)Ar and Bct(R)C=C(R)Bct, respectively.Such a mixture of mono- and bis-metallated products is obtained when the benchrotrenic ketones are used as substrates.Starting from benchrotrenic aldehyde 4, however, the exclusive formation of the mono-tricarbonylchromium trans-stilbene 5 takes place.This has been shown to occur by a two-step process.The Nb(III)-induced partial Cr(CO)3 decomplexation of the substrate is followed by the reductive coupling, preferentially between the free aldehyde formed and the benchrotrenic aldehyde.The differences in the reactivity observed are explained in terms of the favored ? (in plane) geometry for the Nb(III)-Lewis acid activation of the carbonyl toward metalloxirane nucleophilic attack.Nb(III) reagent / reductive coupling / benchrotrene / stereoselectivity
