Nickel-catalyzed Branched-Selective ?-Allylation Of Simple Ketones With 1,3-Dienes

Allylation is an important method to construct C-C bond,therefore holds significant importance in organic synthesis and pharmaceutical industry.Conventional allylation reactions are mostly realized with allylic reagents having leaving groups,such as allylic halides,allylic alcohols,allylic alcohol esters,etc.,while effective,such approaches will produce equivalent amount of by-products and therefore are less atomeconomic.In recent years,different types of unsaturated hydrocarbons such as 1,3-dienes,alkynes,allenes have been used as atom-economic allylic precursors in different types of allylation reactions.Owing to their high atom-economic features,such transformations have undoubtedly become an attractive type of chemical transformation in line with the concept of green synthesis.However,there are still some problems in the allylation of unsaturated hydrocarbons as allylation precursors.For example,the range of nucleophiles is limited,simple ketone substrates,because of their weak nucleophilic properties,usually need to be activated in advance to realize the allylation with unsaturated hydrocarbons.As a result,it is of great significance to develop a highly efficient co-catalytic system to realize the atom-economic allylation of simple ketones with unsaturated hydrocarbons.In this thesis,the branched-selective ?-allylation of simple ketones with substituted 1,3-dienes catalyzed by Ni(0)has been developed.Water was used as the only additive in the reaction.Under mild and pH-neutral reaction conditions,the target product was obtained with high efficiency and high regioselectivity.The reaction was suitable for various aliphatic ketones or aromatic methyl ketones and a variety of substituted 1,3-dienes,producing the corresponding allylation products in high efficiency and regioselectivity.On the other hand,1,3-butadiene,as an important chemical feedstock,is widely used in the synthesis of synthetic rubber,synthetic resin,synthetic fiber,latex paint and other chemical materials.However,due to its low boiling point and trend to undergo rapid polymerization,its application in organic synthesis is relatively limited.Based on the mild allylation catalytic system developed by us,we further explored and realized the efficient ?-crotylation of simple ketones with 1,3-butadiene.Different types of aliphatic ketones as well as aromatic methyl ketones all showed good reactivity.