We have developed a direct regio- and chemoselective method for generating functionalized aromatic cuprate compounds through deprotonative directed ortho cupration using TMP(tetramethylpiperidino)-cuprates (R(TMP)Cu(CN)Li2; R = alkyl, phenyl, or TMP) that are prepared by mixing of CuCN, RLi, and lithium tetramethylpiperidide (LTMP) in THF. Deprotonative cupration of various functionalized benzenes with TMP-cuprate proved effective for the direct generation of o-functionalized copper aromatic and heteroaromatic derivatives, particularly those with electrophilic functional groups, such as cyano, amide, and halogens. Direct cupration, followed by electrophilic trapping, provided a convenient preparative method for 1,2- or 1,2,3-multisubstituted aromatic compounds. The functionalized aromatic cuprate intermediates were also found to undergo oxidation reactions very efficiently and with high regio- and chemoselectivity to afford functionalized phenol, ligand(hetero)-coupling, or homocoupling products by appropriately changing the oxidants and cuprates.
The gene of a novel O-methyltransferase was isolated from tea cultivars (Camellia sinensis L.). Using the recombinant enzyme, O-methylated (-)-epigallocatechin-3-O-gallate (EGCG) in all cases were synthesized. EGCG and the synthesized O-methylated EGCGs including (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3''Me), (-)-epigallocatechin-3-O- (4-O-methyl)-gallate(EGCG4''Me), (-)-epigallocatechin-3-O-(3,5-O-dimethyl)-gallate (EGCG3'',5''diMe), and (-)-3-O-methyl-epigallocatechin-3-O-(3,5-O-dimethyl)-gallate (EGCG3',3'',5''triMe) were assayed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and antibacterial activity. EGCG was the most effective of the O-methylated EGCGs. The antiallergic effects of EGCG and the other O-methylated EGCGs were measured by conducting histamine release assays using bone marrow-derived mouse mast cells, and the order of potency was EGCG3',3'',5''triMe = EGCG3'',5''diMe > EGCG3''Me > EGCG. These results indicated that reducing the number of hydroxyl groups decreases the effectiveness of DPPH radical scavenging and antibacterial activity. In contrast, the inhibition of histamine release was potentiated by an increase in the number of methyl groups in EGCG, especially in the galloyl moiety.
The name of the game: X‐ray crystallographic analysis of Gilman‐ and Lipshutz‐type amidocuprates indicates that the presence of LiX (X=CN, I) and THF shifts the equilibrium between the two toward the Lipshutz‐type cuprate and that this is important in generating the active species for directed ortho cupration. DFT calculations show that monomeric Gilman‐type cuprates have an unprecedentedly high reactivity (see scheme, DG=directing group).
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