Design and Synthesis of C4‐Symmetric Axially Chiral β‐Aryl Porphyrins and Application for Supporting Ir(III)‐Catalyzed Enantioselective C−H Alkylation

A hitherto unknown class of C4‐symmetric Caryl−Cβ (C3, C8, C13, C18) axially chiral porphyrins has been synthesized and the application of their iridium (Ir) complexes in catalytic asymmetric C(sp3)−H functionalization is documented. Cyclotetramerization of enantioenriched axially chiral 2‐hydroxymethyl‐3‐naphthyl pyrroles under mild acidic conditions affords, after oxidation with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ), the C4‐symmetric α,α,α,α‐atropenantiomer as an only isolable diastereomer. Both regioisomeric Ir(Por*)(CO)(Cl) complexes catalyze the carbene C−H insertion reaction affording the same enantiomer, albeit with slight difference in enantioselectivity. With the optimum Ir‐complex 3 e, the 2‐substituted arylacetic acid derivatives were generated from diazo compounds and cyclohexadiene in excellent yields and enantioselectivities. Cyclotetramerization of 2‐hydroxymethyl‐3‐aryl‐pyrroles affords a novel class of C4‐symmetric Caryl−Cβ (C3, C8, C13, C18) axially chiral porphyrins in good yields. Both regioisomers of the Ir‐complex catalyze efficiently the carbene C(sp3)−H insertion reaction.