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Abnormal cyclopalladation of Schiff bases made of metallocenyl aldehydes and α-ferrocenylethylamine: Unexpected formation of the heteroannular 3-atomic bridge

“…Recently many publications have appeared devoted to organometallic derivatives of Schiff bases (aldimines and ketimines) in ferrocenyl series [1][2][3][4][5][6]. Synthetic approaches have been elaborated such as direct mercuration [1,2], cyclopalladation [3,4], cycloplatination [5] as well as transmetalation [6].…”

“…Synthetic approaches have been elaborated such as direct mercuration [1,2], cyclopalladation [3,4], cycloplatination [5] as well as transmetalation [6]. Azomethines derived from a-carbonyl derivatives of ferrocene and primary amines, mostly arylamines, served as models for cyclopalladation, and regioselectivity of the reaction was demonstrated since palladium atom enters into position 2 of the cyclopentadienyl ring of metallocene exclusively, in spite of the presence of aryl group which might form stable five-or six-membered chelated palladacycle.…”