Regioselective CH Bond Activation on Stabilized Nitrogen Ylides Promoted by Pd(II) Complexes: Scope and Limitations

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• 作者：Loreto Grande ; Elena Serrano ; Luciano Cuesta ; Esteban P. Urriolabeitia
• 刊名：Organometallics
• 出版年：2012
• 出版时间：January 9, 2012
• 年：2012
• 卷：31
• 期：1
• 页码：394-404
• 全文大小：553K
• 年卷期：v.31,no.1(January 9, 2012)
• ISSN：1520-6041

文摘

The orthopalladation of N-ylides [H_xC_yN鈥揅HC(O)Ar] (H_xC_yN = pyridine, benzylamine, imidazole, aniline, and phenylpyridine; Ar = aryl) has been studied. The incorporation of the Pd atom to these substrates is regioselective, since the orthopalladation is produced, in most of the cases, only at the aryl ring of the benzoyl group with concomitant C-bonding of the N-ylide. The X-ray structure of one representative example is reported. Factors governing the observed orientation are discussed, because this regioselectivity is worthy of note, considering the deactivating nature of the carbonyl group. Two exceptions to the general trend have been observed. The first one is the double metalation of the ylide [PhMe₂NCHC(O)Ph], which incorporates one Pd at each Ph. The second one is the palladation of the phenylpyridine derivative, which occurs at the pyridinic 2-phenyl ring and produces a six-membered palladacycle.