Five‐membered metallacycles are typically reluctant to undergo endocyclic β‐hydrogen elimination. The rhodium‐catalyzed isomerization of 4‐pentenals into 3‐pentenals occurs through this elementary step and cleavage of two CH bonds, as supported by deuterium‐labeling studies. The reaction proceeds without decarbonylation, leads to trans olefins exclusively, and tolerates other olefins normally prone
五元
金属环通常不愿进行环内β-氢消除。在
氘标记研究的支持下,
铑的催化将
4-戊烯醛异构化为
3-戊烯醛,这是通过该基本步骤和两个CH键的裂解而实现的。反应在不进行脱羰基的情况下进行,仅产生反式烯烃,并耐受通常易于异构化的其他烯烃。还可以在外消旋混合物的对映发散反应中控制环内β-氢的消除。