The copper(II) catalyzed enantioselective 1,4-addition reactions of diethylzinc to cyclic enones in the presence of novel phosphorus amidite ligands, easily prepared from α,α,α',α'-tetraphenyl-2,2'-dimethyl-1,3- dioxolane-4,5-dimethanol (TADDOL) derivatives, resulted in e.e.s up to 71% for cyclohexenone and up to 62% for cyclopentenone. A remarkable enhancement of enantioselectivity was observed upon the addition of powdered molecular sieves to the reaction mixture.
Indigenous Papuans on the western half of the island of New Guinea, have experienced intersecting environmental, social, and political crises, within the context of a movement seeking self-determination. These ongoing crises are exacerbated by longstanding grievances over the Grasberg mine (which contains significant reserves of copper and gold), and environmental degradation caused by the mining and palm oil sectors, as well as the legacy of colonialism on the allocation of land and resources.
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