Cu -catalysed

In organic solvents Lewis-acid catalysis also leads to large accelerations of the Diels-Alder reaction. Table 2.2 shows the rate constants for the Cu -catalysed Diels-Alder reaction between 2.4a and 2.5 in different solvents. 

Table 2,3, Apparent second-order rate constants (M" s ) of the Cu -catalysed Diels-...

Table 2.10. Substituent effect on the selectivity of the Cu catalysed reaction of 2.4 with 2.5 in water at25°C.

Scheme 2.10 Intermediates in the Cu-catalysed hydrosilylation of carbonyl compounds...

The phenothiazines, chlorpromazine and promethazine, have been described as inhibitors of CCU-induced lipid peroxidation at relatively high concentrations in rat liver microsomes (Slater, 1968). Structural modifications of chlorpromazine were undertaken to try to increase antioxidant activity and maintain molecular lipophilicity. The 2-N-N-dimethyl ethanamine methanesulphonate-substituted phenothiazine (3) was found to be a potent inhibitor of iron-dependent lipid peroxidation. It was also found to block Cu -catalysed oxidation of LDL more effectively than probucol and to protect primary cultures of rat hippocampal neurons against hydrogen peroxide-induced toxicity in vitro (Yu et al., 1992). 

Scheme 1.64 Cu-catalysed allylic substitution of cinnamyl phosphate with ZnEt2 in the presence of P-aminosulfonamide ligands.

Scheme 1.66 Cu-catalysed allylic alkylations of allylic phosphates with vinylalumi-num reagents in the presence of sulfur-containing diaminocarbene ligands.

Scheme 1.83 Cu-catalysed substitutions of allylic acetates by RMgX with ferroce-nylthiolate ligand.

Scheme 2.2 Cu-catalysed 1,4-additions of ZnEt2 and AlMe3 to ( )-3-nonen-2-one with 1,1 -binaphthalene-derived ligands.

Cu-catalysed additions of ZnEt2 to Baylis-Hillman-derived allylic electrophiles with BINOL-based thioether ligand. 

Scheme 2.8 Cu-catalysed addition of w-BuMgCl to cycloheptenone with TADDOL-derived ligands.

Scheme 2.9 Cu-catalysed 1,4-addition of ZnEt2 to 2-cyclohexenone with thioether-alcohol ligands bearing xylofuranose backbone.

Scheme 2.13 Cu-catalysed 1,4-addition of AlMcj to 4,4-disubstituted cyclohexa-2,5-dienone with thioether ligands.

Scheme 2.18 Cu-catalysed 1,4-additions of RMgl to acyclic enones with arenethio-latocopper (I) complex.

On the other hand, chiral sulfur-containing but noncoordinating ligands such as sulfonamides have been widely used in the asymmetric Michael reaction. In 1997, Sewald et al. reported the use of a series of chiral sulfonamides depicted in Scheme 2.25 in the Cu-catalysed conjugate addition of ZnEt2 to 2-cyclohexenone. Even the use of a stoichiometric amount of catalyst did not allow the enantioselectivity to be higher than 31% ee. 

Scheme 2.26 Cu-catalysed 1,4-additions of Me2CuLi and ZnEt2 to enones with sulfonamide or bis(sulfonamides) ligands.

Scheme 5.1 Cu-catalysed Diels-Alder reactions with siam ligands.

Scheme 5.2 Cu-catalysed Diels-Alder reaction with siam ligand and sulfinyl imine...

Scheme 5.9 Cu-catalysed hetero-Diels-Alder reactions with C2-symmetric bis(sul-foximines) ligand.

Scheme 5.15 Cu-catalysed Diels-TUder reaction with roofed 2-thiazoline ligands.

In addition, the same group has used copper complexes of these ligands as efficient catalysts for enantioselective Cu-catalysed aza-Diels-Alder reactions of A-sulfonyl imines with Danishefsky s dienes, providing the corresponding six-membered heterocycles with enantioselectivities of up to 80% ee. ... 

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