Comparative Study of the Reactions of Two Alkynes and an Alkene with Chiral Cyclopalladated Complexes Derived from N,N-Dimethyl-α-(2-naphthyl)ethylamine and N,N-Dimethyl-α-methylbenzylamine:  Insertion or Cycloaddition

• Published in: Organometallics 2002-05, Vol.21 (10), p.2041-2048
• Main Authors: Gül, Nizamettin, Nelson, John H, Willis, Anthony C, Rae, A. David
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om0200306

The chiral cyclopalladated complexes containing coordinated 3,4-dimethyl-1-phenylphosphole, DMPP, and an N-donor ligand, (S C)-1 or (S C)-3, reacted with dimethylacetylene dicarboxylate, DMAD, and diphenylacetylene to produce exclusively the insertion products (S C)-2, (S C)-4, (S C)-5, and (S C)-6, respectively, although [4+2] Diels−Alder cycloaddition reactions between DMAD or diphenylacetylene and coordinated DMPP were possible. N-Phenylmaleimide underwent [4+2] Diels−Alder cycloaddition to the coordinated DMPP in the insertion product (S C)-2 to form two stereoisomers of (S C)-7 in a 1.55:1 ratio. However, under similar conditions the insertion product (S C)-4 did not react with N-phenylmaleimide. Complexes (S C)-1 and (S C)-3 reacted with N-phenylmaleimide to give only one enantiomer of the [4+2] Diels−Alder cycloaddition product, although two diastereomeric products were possible in each reaction. The cycloaddition product (S C)-8 reacted with DMAD to give only one stereoisomer of the insertion product (S C)-7, but under similar conditions the cycloaddition product (S C)-9 did not react with DMAD. New complexes were characterized by elemental analyses, physical properties, polarimetry, 1H, 1H{31P}, 13C{1H}, and 31P{1H} NMR spectroscopy, and in several cases X-ray crystallography.