Diene bisamidation

In the crystal structures of the La3+ and Eu3+ complexes of Ln( 18-DTPA-dien) oligomerization was observed [20]. The coordination of the Ln3+ ion by each DTPA unit, however, was similar to that in the linear bisamides. Vapor pressure osmometry indicated that oligomerization in solution does not occur under the conditions applied (0.2-0.5 M). Because of the constraints imposed by linking the two amide functions in the macrocycle, the isomers 1,1 and 3,3 depicted in Fig. 1 are sterically very unfavorable. In line with this, resonances for only two pairs of enantiomers were observed in the 11 spectra of the Ln( 18-DTPA-dien) complexes. The dynamic behavior showed that one pair was rather static, whereas the other was rapidly interconverting. The AG for the interconversion (65 kj mol-1) was about the same as those observed for the SS AA isomerization in other DTPA-derivatives. In the Ln( 18-DTPA-dien) complex such an isomerization is only possible between mirror images 2 and 2. All other isomerizations require decoordination and, therefore, are much slower. 

Dinitriles such as (17) can be used to prepare bisamides or, alternatively, can provide an excellent source of polyamides if glycol, diene, or aldehyde - carbenium ion sources are utilized. 

Palladium-catalysed bisamidation of diene (116) has been attained with (117) as the reagent. Enantiomerically enriched product (118) was obtained (91% ee) in the presence of the axially chiral BINOL-derived phosphoramidites. DFT calculation revealed agostic interactions of the ligand with Pd (in addition to the normal chelation) and the C-W-n interaction between the diene and the aromatic system of the ligand these effects are believed to contribute to the stereoselctivity. ... 

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