Organometallic Complexes of Bulky, Optically Active, C3-Symmetric Tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (ToP*)

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• 作者：Songchen Xu ; Yitzhak Magoon ; Regina R. Reinig ; Bradley M. Schmidt ; Arkady Ellern ; Aaron D. Sadow
• 刊名：Organometallics
• 出版年：2015
• 出版时间：July 27, 2015
• 年：2015
• 卷：34
• 期：14
• 页码：3508-3519
• 全文大小：559K
• ISSN：1520-6041

文摘

A bulky, optically active monoanionic scorpionate ligand, tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate (To^P*), is synthesized from the naturally occurring amino acid l-valine as its lithium salt, Li[To^P*] (1). That compound is readily converted to the thallium complex Tl[To^P*] (2) and to the acid derivative H[To^P*] (3). Group 7 tricarbonyl complexes To^P*M(CO)₃ (M = Mn (4), Re (5)) are synthesized by the reaction of MBr(CO)₅ and Li[To^P*] and are crystallographically characterized. The 谓_CO bands in their infrared spectra indicate that 蟺 back-donation in the rhenium compounds is greater with To^P* than with non-methylated tris(4S-isopropyl-2-oxazolinyl)phenylborate (To^P). The reaction of H[To^P*] and ZnEt₂ gives To^P*ZnEt (6), while To^P*ZnCl (7) is synthesized from Li[To^P*] and ZnCl₂. The reaction of To^P*ZnCl and KOtBu followed by addition of PhSiH₃ provides the zinc hydride complex To^P*ZnH (8). Compound 8 is the first example of a crystallographically characterized optically active zinc hydride. We tested its catalytic reactivity in the cross-dehydrocoupling of silanes and alcohols, which provided Si-chiral silanes with moderate enantioselectivity.