Addition of MeMgSnBu3 to the conjugated enynes 1 and 5 were thoroughly studied. The addition reactions were proceeded stereoselectively at -20 degrees C, but a thermal isomerization occurred when the reaction was carried out at 0 degrees C. (2E,4Z,6E)-Dehydrodendrolasin 8 was synthesized using the isomerized 2-methyl-1-iodo-1,3-diene product 13.
Nickel-catalyzed reductive 1,3-diene formation from the cross-coupling of vinyl bromides
作者:Yunfei Sha、Jiandong Liu、Liang Wang、Demin Liang、Da Wu、Hegui Gong
DOI:10.1039/d1ob00791b
日期:——
Facile construction of 1,3-dienes building upon cross-electrophile coupling of two open-chain vinyl halides is disclosed in this work, showing moderate chemoselectivities between the terminal bromoalkenes and internal vinyl bromides. The present method is mild and tolerates a range of functional groups and can be applied to the total synthesis of a tobacco fragrance solanone.
Rearrangement of Allylic and Propargylic Alcohols Catalyzed by the Combined Use of tetrabutylammonium perrhenate (VII) and p-toluenesulfonic acid
作者:Koichi Narasaka、Hiroyuki Kusama、Yujiro Hayashi
DOI:10.1016/s0040-4020(01)88874-8
日期:1992.1
Allylic rearrangement and/or dehydration reaction of allylic alcohols proceeds smoothly by the use of catalytic amounts of tetrabutylammonium perrhenate and p-toluenesulfonic acid hydrate. Treatment of propargylic alcohols with the catalysts at room temperature affords the rearranged products, α,β-unsaturated carbonyl compounds, while, β,γ-unsaturated ketones are obtained as main products by the reaction
Sulfur‐based olefination with Horner–Wadsworth–Emmons‐type mechanism is systematically studied. Nonstabilized and semistabilized carbanion precursors react with carbonyl compounds giving good yields of olefins, and for the latter reagents E isomers of alkenes predominate.