Kinetics and Mechanism of the Addition of Benzylamines to ¥â-Cyanostilbenes in Acetonitrile

Bulletin of the Korean chemical society

Ikchoon Lee¹  In Kon Kim¹  Dae Dong Sung¹  Hyuck Keun Oh¹ 

关键词: Nucleophilic addition;    ¥â-Cyanostilbene;    Cross-interaction constant;    Kinetic isotope effects;    Concerted mechanism;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

Nucleophilic addition reactions of benzylamines (XC6H4CH2NH2) to �?-cyanostilbenes (YC6H4CH=C(CN)C6H4Y�?) have been studied in acetonitrile at 30.0 oC. A greater degree of N-C �? bond formation (larger モX) is obtained with a stronger electron-withdrawing substituent in either �?- ( ヤヲY > 0) or �?-ring ( ヤヲY�? > 0). A stronger charge development is observed in the TS on C �? ( ヱY�? = 1.06 for X=Y=H) rather than on C �? ( ヱY = 0.62 for X=Y�?=H) indicating the lag in the resonance development into the activating group (CN) on C �? in the transition state. Similarly, the magnitude of ヱXY�? (?0.72) is greater than ヱXY (?0.66) due to a stronger interaction of the nucleophile with �?-ring than �?-ring. The positive sign of ヱYY�? correctly reflects �? bond cleavage between the two rings in the TS. Relatively large kinetic isotope effects (kH/kD �? 2.0) involving deuterated nucleophiles (XC6H4CH2ND2) suggest a four-membered cyclic TS in which concurrent N-C �? and H(D)-C �? bond formation occurs.

【 授权许可】

Unknown