Herstellung enantiomerenreiner 5‐Palladatricyclo[4.1.0.0^2,4]heptane und deren Umsetzung zu enantiomerenreinen, helical chiralen Pd‐Komplexen

Abstract

Bis zu 30° sind die C‐Pd‐C‐ und die P‐Pd‐P‐Ebene in den helical chiralen Komplexen 2 gegeneinander gekippt, was für PdII‐Komplexe eine unerwartete Abweichung von der quadratisch‐planaren Koordination bedeutet. Hergestellt wurde 2 ( = 1,1′‐Ferrocendiyl) aus dem entsprechenden zweizähnigen Phosphanliganden und dem bemerkenswert stabilen, in guten Ausbeuten und auch enantiomerenrein zugänglichen Bishomo‐Palladol 1. E = CO2Me.

Bioconjugates of Enantiomerically Pure Organopalladium Compounds by Metal‐Assisted Positional Selective Transesterifications at Palladium Enolates

“…The complex shows C 2 symmetry, and the palladium-carbon bond lengths of 2.051 are typical for this class of compounds; the same is true for the tilt of 16.88 between the plane of the bipyridine (bpy) ligand and the plane of the palladacyclopentane substructure. [4] The reaction proceeded rapidly at room temperature, the other two methyl esters remained untouched even after long reaction times or elevated temperatures (50 8C). Such reactivity has, to the best of our knowledge, not yet been reported for any palladium esterenolate complexes.…”

“…A second Sonogashira coupling of (1S,2S,4S,6S)-16 with N-dansylpropargylamine, followed by removal of the bpy ligand, [4] gave steroid-PdTH-dye conjugate 17 in 53 % yield (see Scheme 7), which unfortunately showed only weak fluorescence. To overcome this problem, the stereoisomers of 5 m were transesterified with 6-bromohexanol, which led to enantiomerically pure (1S,2S,4S,6S)-5 r and (1R,2R,4R,6R)-5 r (Table 2, entry 4).…”

“…[1] on derivatives of type 1, which require stabilization by strongly coordinating ligands, and the work of Maitlis et al [2] on palladoles 2, which are resistant to oxygen and heat without such stabilizing ligands, we reported the synthesis, [3] resolution, [4] stereoselective synthesis, [5] and stoichiometric [6] and catalytic [7] chemistry of palladacycles of type 4.…”

“…[5] This, together with their C-bound palladium ester enolatetype substructure, differentiates them from other similar Abstract: The synthesis of enantiomerically pure palladatricyclo-A C H T U N G T R E N N U N G [4.1.0.0 2,4 ]heptanes and their modification by an unprecedented and very efficient positional selective transesterification is described. The mild reaction conditions are most probably based on an acceleration of the transesterification due to assistance by the metal.…”

Asymmetric Synthesis of Palladacycles by Regioselective Oxidative Cyclization of C2-Symmetrical, Chiral Alkenes and Determination of the Configuration of All Stereocenters

“…In each case in the NMR spectra only the set of signals one would expect for a C 2 -symmetrical trans -PTH was visible . We wanted to ensure that there was no accidental isochronism caused by the large distance between the stereocenters in the lactate side chains and the palladacycle.…”