Controlling Stereochemical Outcomes of Asymmetric Processes by Catalyst Remote Molecular Functionalizations: Chiral Diamino‐oligothiophenes (DATs) as Ligands in Asymmetric Catalysis

Abstract

The synthesis, characterization, and structure-guided application of a new class of highly versatile chiral C(2)-symmetric diamine-oligothiophene ligands in Pd-catalyzed asymmetric transformations are presented. Experimental investigations of the intimate role of pendant pi-conjugate oligothiophenes in determining the catalytic activity of the corresponding chiral Pd complexes are described. Their unusual behavior opens up new routes toward the logical design of finely tuned organometallic catalysts by remote structural functionalizations.

Orbital Interaction and Electron Density Transfer in PdII([9]aneB2A)L2 Complexes: Theoretical Approaches

“…In this context, the achievements in development of novel and efficient synthetic methodologies for these types of reactions have been acknowledged with the 2010 Nobel Prize in Chemistry. Much attention has been paid to the design and development of powerful Pd-catalysts/precursors [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,37,38,39,40,41,42,43] that contain bulky and electron-rich ligands (such as phosphines and N -heterocyclic carbenes, NHCs) and to their potential synthetic applications [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36] in the Pd-catalyzed cross-couplings of various substrates (such as allyl, aryl, and vinyl halides and olefins). Catalytic activity enhancement of Pd (0) ( L ) n -precursors is greatly influenced by the electronic and steric properties of electron-rich and bulky L- ligands [1,2,3,4,5,6,7,8,18,19,20,21,22,23,24…”

“…The geometric structures of the active RPd( L ) n X intermediates produced in various steps of Pd-mediated cross-coupling reactions (e.g., oxidative addition, transmetalation, reductive elimination) have been investigated both theoretically [9,10,11,12,13,14,15,16,17] and experimentally [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42]. The oxidative addition of substrates (R-X) to Pd L n -precursor resulted in penta-, hexa-, and octacoordinate geometries [33,34,35,36] of the RPd II ( L ) n X intermediates with relative stability and a life time of 30 s [3].…”

“…In previous studies using hemilabile multidentate ligands [37,38,39,40,41,42,43,44,45,46,47], exceptional oxidation state and specific coordination selectivity have been observed for the Pd([9]ane B 2 A ) L 2 complexes with mixed soft A and hard B tridentates. The uncommon geometric structures of Pd([9]ane B 2 A ) L 2 complexes with an axial ( A …Pd) interaction were mainly formed under the following restrictive conditions: (1) coordination bonds of P - and N -functionalized derivatives are present [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39] and (2) polymeric side chain interactions exist [40,41,42]. In the Pd complex with an apical (hard N …Pd) interaction [42], the apical interaction was explained by an antibonding interaction between the lone pair of the apical N site and the d z2 -orbital of the Pd II species.…”

New adaptive chiral thiophene ligands for copper‐catalyzed asymmetric Henry reaction

“…In this field, we recently reported on the effectiveness of a new family of chiral C2-symmetric diamino ligands, bearing oligothienyl groups of various lengths, in several asymmetric transformations such as allylic alkylation, 6,7 hydrosylilation of ketones, 8 and Henry condensations (Fig. 1).…”

New Recoverable Poly(ethylene glycol)‐Supported C1‐Diamino‐oligothiophene Ligands for Palladium‐Promoted Asymmetric Allylic Alkylation (AAA) Reactions

“…In analogy with the homogeneous DATs applications, [7] we chose to test the new PEG-C 1 -DATs 7a and 7b in the model reaction depicted in Scheme 2, and we examined the generality of the protocol by applying the supported catalysts to different linear hindered and unhindered allyl carbonates (8a-c). In Table 1 we summarise a collection of results obtained during the survey of reaction conditions.…”