Study On Copper-Catalyzed Reductive Allylation Of Allenes

1,5–diene skeletons are abundant in biologically active compounds and pharmaceuticals,playing an indispensable role in biological activity,such as insecticidal milbemycin?₃,antibiotics rottnestol,anti-tumour herboxidiene,and NADH fumarate reductase inhibitor nafuredin.They are also important synthetic intermediates,having extensive application in the field of total synthesis.Therefore,the approaches for efficient regioselective installation of these subunits has attracted considerable attention in organic synthetic chemistry.Transition metal catalyzed allylation has been widespread concerned by the organic chemists since it was found,because viaing these methods not only establish a new C–C bond,but introduce a versatile allyl functional groups.The traditional precious metals?Ir,Pd?catalyzed allylation reaction utilizing soft nucleophilic reagent?p Ka<25 nucleophiles?has been deeply studied in the field of organic synthesis.however,the cheap metal?Ni,Cu?catalyzed allylation received less attention using hard nucleophilic reagent?pKa>25nucleophiles?such as:grignard reagents,organic zinc reagents,organic boron reagents and so on recently.moreover,organic metal reagents with poor functional groups compatibility,the preparation steps trival,not stable,and not easy storage.therefore,developing a new method that substitutes organic reagent is very important.In numerous allylation methods,one straightforward method for 1,5–dienes is the transition metal catalyzed allyl-allyl cross-coupling of allyl electrophiles and allyl nucleophiles,and an inherent challenge is the difficulty in controlling regioselectivity of the reaction,besides,it also need to amount of organic metal reagents involved in.Therefore,developing an environment friendly synthetic method for high regioselective 1,5–diene compounds is very urgent.As everyone knowns,organocopper reagents have been widely used in C–C bond forming reactions.One of the most powerful processes to form Cu–C bond is the addition of Cu–H across C–C multiple bonds?hydrocupration?.Allenes is a class of unsaturated hydrocarbon compounds,and has the characteristics of high reactivity and multiple reactive sites,which can form an allyl copper nucleophile through hydrocupration reacts with electrophiles to produce various 1,5–dienes.The copper–catalyzed allyl-allyl cross-coupling reaction of allenes has been successfully achieved by employing a hydrosilane and allylic phosphate electrophiles in a Cu–H catalyzed process.The bidentate IPr N-heterocyclic carbene ligated Cu I complex delivers S_N2-type1,5–dienes in good to high yields with high regioselectivity.The present transformation proceeded with mild conditions and various functional groups proved to be compatible,having the characteristics of high yield and high regioselectivity and avoiding the use of allyl metal reagents.