Sodium Acetate-catalyzed Regiospecific and High Stereose- lective Aminobromination of β,β-Dicyanostyrene Derivatives with NBS as Nitrogen/Bromine Source

An easy and efficient method for the aminobromination of β,β-dicyanostyrene derivatives with NBS as the aminobrominating reagent in CH3CN catalyzed by NaOAc （10 mol%） is developed. This protocol provides con- venient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines with full regiospecificity and high stereoselectivety in the ice-water bath in air. The reaction is high efficient in yielding the corresponding ami- nobrominated products in excellent yields （up to 95%） under these conditions. The outcome indicated that the reac- tion has an electrophilic addition feature. 12 Eexamples of β,β-dicyanostyrene derivatives have been investigated.

One-pot Synthesis of α,β-Dehydroamino Derivatives from β,β-Dicyanostyrene with 1,3-Dibromo-5,5-dimethylhydantoin Promoted by Mild Base

The reaction of β,β-dicyanostyrene derivatives（l） with 1,3-dibromo-5,5-dimethylhydantoin（DBDMH） was systematicly studied. The reaction could generate different products when promoted by different mild bases. When the reaction was promoted by NaOAc（100%, molar ratio to compound 1）, β,β-dicyanostyrene derivatives could be directly converted into corresponding α,β-dehydroamino derivatives in good to excellent yields in one-pot. When the reaction was promoted by K3PO4（80%, molar ratio to compound 1）, the corresponding α,β-dehydroamino and double-α,β-dehydroamino compounds were simultaneously obtained and the total conversion of β,β-dicyanostyrene derivatives was up to 90% or higher.

K3PO4-Catalyzed Regiospecific Bromoamidation of β, β-Dicyanostyrene Derivatives with N-Bromoacetamide（NBA）

An efficient method for the bromoamidation of β,β-dicyanostyrene derivatives with N-bromoacetamide （NBA） was developed.This protocol provides a convenient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines in excellent yields（up to 99％） at room temperature in the presence of anhydrous K3PO4 as a catalyst without the protection of the inert gaseous in CH2Cl2.A total of 11 examples were investigated and all the products showed the regionspecific feature.Based on the observation of different activities for the different substrates involving the electron-rich or electron-deficient β,β-dicyanostyrenes,a possible Michael addition mechanism was proposed.

Base-catalyzed Formation of Enamines from β,β-Dicyanostyrene Derivatives with N-Bromosaccharin

A new method for the synthesis of functional enamines from β,β-dicyanostyrene derivatives and N-bromosaccharin（NBSA） was developed. In the presence of Na2CO3, the the reaction of β,β-dicyanostyrene derivatives with NBSA can generate the corresponding enamines smoothly in a mixed solvent of dichloromethane and N,N-dimethylformamide（DMF）（volume ratio 1：1） at 50 ℃. The reaction of 14 kinds of β,β-dicyanostyrene derivatives with NBSA was investigated. Screened olefins afforded the corresponding enamines in good to excellent yields（up to 94%）, indicating that the method has a wide adaptability for the substrate. The catalyst used is inexpen- sive and stable for storage. The amino groups of all products in their structures are on the a-position of products, revealing the reaction has an excellent regioselectivity. The possible pathway involving aminobromination of β,βdicyanostyrene derivative with NBSA first and then elimination of HBr process in one pot has been proposed. The structures of all products were confirmed by ^1H NMR, ^13C NMR and HRMS analysis.