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Highly Enantioselective Total Synthesis of (+)-Isonitramine

N2 - In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, N-arylation (aromatic amination) of various o-tert-butylanilides with p-iodonitrobenzene proceeds with high enantioselectivity (88-96% ee) to give atropisomeric N-(p-nitrophenyl)anilides having an N-C chiral axis in good yields. Atropisomeric anilide products highly prefer to exist as the E-rotamer which has trans-disposed o-tert-butylphenyl group and carbonyl oxygen. The application of the present catalytic enantioselective N-arylation to an intramolecular version gives atropisomeric lactam derivatives with high optical purity (92-98% ee). The reaction of the lithium enolate prepared from the atropisomeric anilide and lactam products with various alkyl halides gives α-alkylated products with high diastereoselectivity (diastereomer ratio = 13:1 to 46:1).

T1 - Organocatalytic highly enantioselective synthesis of β-Formyl-α- hydroxyphosphonates

AB - The cross-aldol reaction between enolizable aldehydes and α-ketophosphonates was achieved for the first time by using 9-amino-9-deoxy-epi-quinine as the catalyst. β-Formyl-α- hydroxyphosphonates were obtained in high to excellent enantioselectivities. The reaction works especially well with acetaldehyde, which is a tough substrate for organocatalyzed cross-aldol reactions. The products were demonstrated to have anticancer activities.

Highly enantioselective synthesis of isoxazoline N …

T1 - Highly enantioselective synthesis of atropisomeric anilide derivatives through catalytic asymmetric N-arylation

The cross-aldol reaction between enolizable aldehydes and α-ketophosphonates was achieved for the first time by using 9-amino-9-deoxy-epi-quinine as the catalyst. β-Formyl-α- hydroxyphosphonates were obtained in high to excellent enantioselectivities. The reaction works especially well with acetaldehyde, which is a tough substrate for organocatalyzed cross-aldol reactions. The products were demonstrated to have anticancer activities.

N2 - The cross-aldol reaction between enolizable aldehydes and α-ketophosphonates was achieved for the first time by using 9-amino-9-deoxy-epi-quinine as the catalyst. β-Formyl-α- hydroxyphosphonates were obtained in high to excellent enantioselectivities. The reaction works especially well with acetaldehyde, which is a tough substrate for organocatalyzed cross-aldol reactions. The products were demonstrated to have anticancer activities.

Highly enantioselective synthesis of isoxazoline N-oxides

Protecting-group-free synthesis as an opportunity for invention, Nature Chemistry, 2009, 1, 193-205.

In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, N-arylation (aromatic amination) of various o-tert-butylanilides with p-iodonitrobenzene proceeds with high enantioselectivity (88-96% ee) to give atropisomeric N-(p-nitrophenyl)anilides having an N-C chiral axis in good yields. Atropisomeric anilide products highly prefer to exist as the E-rotamer which has trans-disposed o-tert-butylphenyl group and carbonyl oxygen. The application of the present catalytic enantioselective N-arylation to an intramolecular version gives atropisomeric lactam derivatives with high optical purity (92-98% ee). The reaction of the lithium enolate prepared from the atropisomeric anilide and lactam products with various alkyl halides gives α-alkylated products with high diastereoselectivity (diastereomer ratio = 13:1 to 46:1).

AB - In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, N-arylation (aromatic amination) of various o-tert-butylanilides with p-iodonitrobenzene proceeds with high enantioselectivity (88-96% ee) to give atropisomeric N-(p-nitrophenyl)anilides having an N-C chiral axis in good yields. Atropisomeric anilide products highly prefer to exist as the E-rotamer which has trans-disposed o-tert-butylphenyl group and carbonyl oxygen. The application of the present catalytic enantioselective N-arylation to an intramolecular version gives atropisomeric lactam derivatives with high optical purity (92-98% ee). The reaction of the lithium enolate prepared from the atropisomeric anilide and lactam products with various alkyl halides gives α-alkylated products with high diastereoselectivity (diastereomer ratio = 13:1 to 46:1).

Total synthesis of marine natural products without using protecting groups, Nature, 2007, 446, 404-408.
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Highly Enantioselective Synthesis of (E)-Allylic Alcohols

The Johnson Group at UNC Chapel Hill focuses on new reaction development, enantioselective catalysis, and natural product synthesis.

Highly enantioselective synthesis of atropisomeric …

Highly enantioselective asymmetric syntheses, , enantioselective addition of alkylmetal reagents to aldehydes and imines, enantioselective conjugate addition of dialkylzincs to enones, and asymmetric autocatalysis have been developed by designing asymmetric catalysts (or chiral ligands) and chiral environment of the reactions. Automultiplication of chiral compounds by asymmetric autocatalysis was discovered where a chiral product acts as a chiral catalyst for its own production. Asymmetric autocatalysis with>99.5% ee in a yield of > 99% was attained using pyrimidyl alkanol as an asymmetric autocatalyst in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde. The asymmetric autocatalysis exhibits significant positive non-linear effect on ee. Asymmetric autocatalyst with very low (. 0.00005%) ee enhances its ee significantly up to > 99.5% ee during the consecutive asymmetric autocatalysis without the assistance of any other chiral auxiliary. Moreover, amino acids and [6] helicene with very low ee which are produced by asymmetric photolysis and photosynthesis using circularly polarized light serve as chiral initiators of asymmetric autocatalysis, and pyrimidyl alkanol with high ee is obtained. Inorganic chiral crystals such as quartz and sodium chlorate, [2.2] paracyclophanes, allenes, chiral cobalt complexes due to the topology of coordination, chiral primary alcohols due to the deuterium substitution also work as chiral initiators. Asymmetric autocatalysis is capable to discriminate efficiently the chirality of various chiral compounds. Moreover, the reactions of pyrimidinecarbaldehyde with diisopropylzinc without adding chiral substance exhibit the formation of enantioenriched S or pyrimidyl alkanols with approximate stochastic distribution, which indicates the reaction is a spontaneous absolute asymmetric synthesis. These results correlate for the first time the proposed origins of chirality of organic compounds with the chirality of organic compounds with very high ee.

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