The migratory insertions of cis or trans olefins CH(X)=CH(Me) (X=Ph, Br, or Et) into the metal– acyl bond of the complex [Pd(Me)(CO)(iPr2ACHTUNGTRENUNGdab)]+ [B{3,5-(CF3)2C6H3}4] (1) (iPr2ACHTUNGTRENUNGdab=1,4-diisopropyl- 1,4-diazabuta-1,3-diene=N,N’-(ethane-1,2-diylidene)bis[1-methylethanamine]) are described (Scheme 1). The resulting five-membered palladacycles were characterized by NMR spectroscopy and X-ray analysis. Experimental data reveal some important aspects concerning the regio- and stereochemistry of the insertion process. In particular, the presence of a Ph or Br substituent at the alkene leads to the formation of highly regiospecific products. Moreover, in all cases, the geometry of the substituents in the formed palladacycle was the same as in the starting olefin, as a consequence of a cis addition of the Pd–acyl fragment to the C=C bond. Reaction with CO and MeOH of the five-membered complex derived from transb- methylstyrene (=[(1E)-prop-1-enyl]benzene) insertion, yielded the 2,3-substituted g-keto ester 9 with an (2RS,3SR)-configuration
Insertion reactions of 1,2-disubstituted olefins with an α -diimine palladium(II) complex / C. CARFAGNA; G. GATTI; L. MOSCA; P. PAOLI; A. GUERRI. - In: HELVETICA CHIMICA ACTA. - ISSN 0018-019X. - STAMPA. - 89:(2006), pp. 1660-1671. [10.1002/hlca.200690164]
Insertion reactions of 1,2-disubstituted olefins with an α -diimine palladium(II) complex
PAOLI, PAOLA;GUERRI, ANNALISA
2006
Abstract
The migratory insertions of cis or trans olefins CH(X)=CH(Me) (X=Ph, Br, or Et) into the metal– acyl bond of the complex [Pd(Me)(CO)(iPr2ACHTUNGTRENUNGdab)]+ [B{3,5-(CF3)2C6H3}4] (1) (iPr2ACHTUNGTRENUNGdab=1,4-diisopropyl- 1,4-diazabuta-1,3-diene=N,N’-(ethane-1,2-diylidene)bis[1-methylethanamine]) are described (Scheme 1). The resulting five-membered palladacycles were characterized by NMR spectroscopy and X-ray analysis. Experimental data reveal some important aspects concerning the regio- and stereochemistry of the insertion process. In particular, the presence of a Ph or Br substituent at the alkene leads to the formation of highly regiospecific products. Moreover, in all cases, the geometry of the substituents in the formed palladacycle was the same as in the starting olefin, as a consequence of a cis addition of the Pd–acyl fragment to the C=C bond. Reaction with CO and MeOH of the five-membered complex derived from transb- methylstyrene (=[(1E)-prop-1-enyl]benzene) insertion, yielded the 2,3-substituted g-keto ester 9 with an (2RS,3SR)-configurationI documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.