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• 1806-29-7 2,2'-dihydroxybiphenyl 

Relevant academic research and scientific papers

A simple iridium catalyst with a single resolved stereocenter for enantioselective allylic amination. Catalyst selection from mechanistic analysis

A study of the relationship between the stereochemical elements of a phosphoramidite ligand and the stereoselectivity of iridium-catalyzed amination of allylic carbonates is reported. During catalyst activation, a complex of a phosphoramidite ligand possessing one axial chiral binaphtholate group and two resolved phenethyl substituents converts to a more reactive cyclometalated complex containing one distal chiral substituent at nitrogen, one substituent that becomes part of the metalacycle, and one unperturbed binaphtholate group. Systematic changes were made to the different stereochemical elements. Replacement of the distal chiral phenethyl substituent with a large achiral cycloalkyl group led to a catalyst that reacts with rates and enantioselectivities that are similar to those of the original catalyst with the phenethyl group. Studies of the reactions of diastereomeric ligands containing (R) or (S) binaphtholate groups on phosphorus, along with one (R)-phenethyl and one achiral cyclododecyl group on nitrogen, show that the complexes of the two diastereomeric ligands undergo cyclometalation at much different rates. To access both diastereomeric catalysts and to determine if the reaction can occur selectively with an even simpler ligand containing a phenethyl substituent at nitrogen as the only resolved stereochemical element, the catalyst derived from a phosphoramidite containing a biphenolate group was studied. Catalysts generated from this ligand were shown to react in all cases examined with nearly the same rates, regioselectivities, and enantioselectivities as catalysts derived from the original more elaborate ligand. The absolute stereochemistry of the product implies that the major enantiomer is formed from the (R a,Rc)-atropisomer of the catalyst containing the biphenolate group.

ENANTIOSELECTIVE PHOSPHORAMIDITE COMPOUNDS AND CATALYSTS

This invention relates to phosphoramidite compounds and catalyst complexes which can be used to provide enantioselective reactions including hydroamination reactions, etherification reactions and conjugate addition reactions and allylic substitution reactions, among others. In a first aspect, the present invention is directed to phosphoramidite and related compounds according to general structure (I), where Z is absent or is a group containing O, N or S, preferably O; R1 and R2 are independently an optionally substituted C1-12 alkyl group, an optionally substituted (CH2)n-aromatic group or (CH2)n-heteroaromatic group, or are linked together to form an optionally substituted aliphatic or (CH2)n-aromatic dianion of a diol, diamine, dithiol, aminoalcohol, aminohiolate or a alcoholthiol group; R3’ and R3 are each independently H, an optionally substituted C1-C12 alkyl group or an optionally substituted (CH2)n-aromatic group with the proviso that R3’ and R3 are not both H, or together R3’ and R3 form an optionally substituted C5-C15 saturated or unsaturated carbocyclic ring; R4 is H, an optionally substituted C1-C12 alkyl group or an optionally substituted (CH2)n-aromatic group; R5 is absent, H, an optionally substituted C1-C12 alkyl group or an optionally substituted (CH2)n-aromatic or (CH2)n-heteroaromatic group; Ra and Ra’ are each independently H or a C1-C3 alkyl group, or Ra and Ra’ together with the carbon to which they are attached form a optionally substituted C5-C15 saturated or unsaturated carbocyclic or heterocyclic ring, or an aromatic or heteroaromatic ring; R6 and R7 are each independently H, an optionally substituted C1-C12 alkyl group or an optionally substituted (CH2)n-aromatic group, with the proviso that R5, R6 and R7 cannot simultaneously be H, and when Ra and Ra’, together with the carbon to which they are attached, form a carbocyclic ring, heterocyclic ring or an aromatic or heteroaromatic ring, R5 is absent or is preferably H; R6 and R7 are preferably H or CH3; and each n is independently 0, 1, 2, 3, 4, 5 or 6 and wherein at least one of the carbon atoms attached to the nitrogen of the phosphoramidite group is a chiral center.