New Aspects of Organocopper Reagents: 1,3- and 1,2-Chiral Induction and Reaction Mechanism

Recent advances in chemo-, regio- and stereoselective reactions of α,β-unsaturated carbonyl compounds with organocoppers and their trifluoroborane complexes are described. Organocopper-Lewis acid reagents are utilized in many key steps for the synthesis of medicinally important natural products. Transition-state models have been proposed to explain the observed regio- and stereochemistries. 1. Introduction 2. Reductive Cleavage by means of Organocopper Reagents 3. Organocyanocopper-Lewis Acid Mediated 1,3-Chirality Transfer of Acyclic (E)-γ-Mesyloxy-α,β-enoates. 3.1 Synthesis of α-Alkyl-β,γ-enolates with High Optical Purity 3.2 (E)-Alkene Dipeptide Isostere Synthesis 3.3 Will Methylcopper Reagents React with γ,δ-Epoxy(E)-α,β-Unsaturated Esters in the Same Manner? 3.4 Determination of Stereochemistry at the α-Position to the Carboxy Group by Circular Dichroism 4. "Higher Order" Zinc Cuprates: The Latest Copper Reagent for the 1,3-Chirality Transfer 5. Rationale of 1,2-Chiral Induction in the Conjugate Addition to γ-Alkoxy α,β-Unsaturated Systems 6. Conclusion