Allyl-, Allenyl-, and Propargyl-Transfer Reactions through Cleavage of CC Bonds Catalyzed by an N-Heterocyclic Carbene/Copper Complex: Synthesis of Multisubstituted Pyrroles
作者:Masahiro Sai、Hideki Yorimitsu、Koichiro Oshima
DOI:10.1002/anie.201100631
日期:2011.3.28
Cat. in the bag: The pictured copper complex can promote CC bond cleavage through retro‐allylation of homoallyl alcohols to form allylcopper species. This process is applicable to catalytic allylation of aldehydes and imines with homoallyl alcohols. The method has also been extended to regioselective allenylation and propargylation of imines.
Directly opposing Keulemans rule! Phosphinites work as reversiblybounddirectinggroups allowing for the first highly regioselective hydroformylation of 3‐substituted homoallylic alcohols to construct quaternary carbon centers. This method enables the atom‐economical synthesis of a wide range of α,α‐disubstituted γ‐lactones and highly substituted tetrahydrofurans (see scheme; R1, R2=alkyl/aryl).
直接反对Keulemans统治!次膦酸盐作为可逆结合的导向基团起作用,从而允许3-取代均烯丙基醇的首次高度区域选择性加氢甲酰化以构建季碳中心。该方法可实现多种α,α-二取代的γ-内酯和高度取代的四氢呋喃的原子经济合成(参见方案; R 1,R 2 =烷基/芳基)。
Manganese-Promoted Oxidative Cyclization of Unsaturated Oximes Using Molecular Oxygen in Air under Ambient Conditions
A highly efficient manganese-promoted oxidative cyclization of unsaturated oximes to afford the corresponding 4,5-dihydroisoxazoline alcohols was developed. A very low loading (generally 0.1–0.2 mol-%) of Mn(acac)3 (acac = acetylacetonate) promoted the oxidative cyclization through the direct incorporation of molecular oxygen present in air (open flask) at room temperature.
The first example of the Wittig rearrangement of furfuryl ethers is presented and its application to the preparation of 3-(2-furyl)-3-hydroxy-2-methylpropionates is described.