Nickel-catalyzed Carboannulation Reaction Of O-halobenzylzinc Bromide With Unsaturated Compounds

Indene derivatives exist in many pharmacological compounds which are widelyused in medicine, agriculture, industry and other fields. There are many kinds ofmethods to prepare indene derivatives, but all have certain disadvantages. In this paperwe dedicated to find a new method for indenes, which is Nickel-catalyzedcarboannulation reaction of o-halobenzyl zinc bromide with unsaturated compounds,and try to find the optimized reaction condition.On the basis of previous studies, we expanded the reaction substrates. Theproducts have been structurally determined by NMR spectra.1. Under the optimized reaction conditions, in the carboannulation reaction of o-BrC6H4CH2ZnBr with alkyne, we investigated the effect on the yield of thesubstituents on the benzene ring in alkyne. The yield in the reaction of the substratewith a electron-donating substituents was higher than that of the substrate withelectron-withdrawing substituents, the numbers and position of the methoxysubstituent on the zinc reagents or the benzene ring in alkyne had small effect on theyield. A total of six indenes had been synthesized by o-BrC6H4CH2ZnBr derivativesand alkyne. They are new compounds.2. A total of two indanes had been synthesized by o-BrC6H4CH2ZnBr derivativesand styrene. They are new compounds.3. We attempted to synthesize indenes with heterocyclic ring zinc reagent, butfailed.4. We attempted to use o-IC6H4CH2ZnBr instead of o-BrC6H4CH2ZnBr, after alarge quantity of tries on the catalysts, additives and solvents, the best reactionconditions had been found. The reaction was carried out by the catalyst withNi(PPh3)212, no additives, CH2Cl2as solvents, the separated yield of indenes was85%at40℃. Contrast with the reaction conditions of o-BrC6H4CH2ZnBr and phenylacetyl-ene, the merits were: shorter reaction time, higher yield. 5. A total of eight indenes had been synthesized by o-IC6H4CH2ZnBr and alkyne,and the products were the same substances with the indenes had been synthesized byo-BrC6H4CH2ZnBr and the same alkyne, but higher yield.6. A total of four indanes had been synthesized by o-IC6H4CH2ZnBr and styrene,and the products were the same substances with the indenes had been synthesized byo-BrC6H4CH2ZnBr and the same styrene, but higher yield.7. In the products of indenes had been synthesized by o-XC6H4CH2ZnBr (X=I,Br) and alkyne, the large substituent was in the2-position of the indene ring, and thesmall substituent was in the3-position of the indene ring. But it was different in theproducts of indanes had been synthesized by o-XC6H4CH2ZnBr (X=I, Br) and styrene,in which, the large substituent was in the1-position of the indane ring.