Asymmetric hydroxylation by a chiral iron porphyrin

Porphyrins as Catalysts in Scalable Organic Reactions

“…Approximately 10 years later, Groves and Viski reported for the first time, the enantioselective hydroxylation of ethylbenzenes catalysed by a chiral iron porphyrin with up to 77% ee using PhIO as oxidant (Scheme 12) [63,64]. When manganese was used, higher yields were obtained, but the enantioselectivity decreased and ketones were also observed as by-products in the catalytic reactions.…”

PdII‐Catalyzed Enantioselective Activation of C(sp2)H and C(sp3)H Bonds Using Monoprotected Amino Acids as Chiral Ligands

“…To test whether this protocol can be extended to enantioselective alkylation of C(sp 3 )ÀH bonds, substrate 21 was subjected to the standard conditions. Poor enantioselectivity (10-15 % ee) was obtained with ligands 7 k, 7 l, and 8 (see the Supporting Information for details).…”

“…The insertion of metal-bound carbenes or nitrenes into CÀH bonds has been employed to develop highly enantioselective carbon-carbon and carbon-nitrogen bond-forming reactions.[1] The enantioselective lithiation of C(sp 3 ) À H bonds adjacent to the nitrogen atom in N-tert-butyloxycarbonylpyrrolidine using secBuLi/(À)sparteine has provided a broadly useful method for the differentiation of prochiral C(sp 3 )ÀH bonds.[2] Investigations into the biomimetic oxidation of CÀH bonds using chiral metal-porphyrin complexes [3] and other synthetic catalysts [4] continue to provide inspiration for the development of methods for the asymmetric oxidation of C À H bonds. Remarkable progress in understanding the fundamental mechanisms of CÀH activation by means of metal insertion [5] has spurred the development of metal-catalyzed carboncarbon and carbon-heteroatom bond-forming reactions in organic molecules containing functional groups.…”

“…With this in mind, we embarked on the development of a Pd II -catalyzed enantioselective CÀH activation/CÀC coupling reaction, a process previously unknown owing to the difficulty in differentiating prochiral CÀH bonds through metal insertions. [9][10][11] Herein we demonstrate a proof of concept by the design of a Pd II /amino acid complex capable of catalyzing asymmetric activation of prochiral C(sp 2 ) À H and C(sp 3 ) À H bonds to form chiral products with new CÀC bonds in excellent enantioselectivity [Eq. (1)].…”

Palladium(II)‐katalysierte C‐H‐Aktivierung/C‐C‐Kreuzkupplung: Vielseitigkeit und Anwendbarkeit

“…[85] Es sind nur wenige Beispiele für die chirale Erkennung von C(sp 3 )-Zentren bekannt; [86][87][88] hierzu gehören die asymmetrische HeckCyclisierung, die asymmetrische Metathese und die kinetische Racematspaltung von Alkoholen. [89] Dennoch konnten im Bereich der enantioselektiven Carbeninsertion in C(sp 3 )-H-Bindungen in den letzten Jahrzehnten beeindruckende Fortschritte erzielt werden.…”