Synthesis and some chemical properties of s-cis-diferrocenyltrienes. The role of stereoelectronic factors in cationic dimerization reactions
摘要:
Dehydration of 2,6-bis(ferrocenylmethylene)-1-methylcyclohexanol and 2,7-bis(ferrocenylmethylene)-1-methylcycloheptanol gave the corresponding diferrocenyltrienes with a fixed s-cissoidal conformation of the double bond system, viz. 1,3-bis(ferrocenylmethylene)-2-methylene-cyclohexane and -cycloheptane, respectively. These trienes easily afford the products of linear and cyclodimerization by a cationic cyclodimerization mechanism as well as [4 + 2]-cyclodimers. They also form Diels-Alder adducts with azodicarboxylic and maleic acid N-phenylimides. The latter products undergo stepwise oxidative dehydrogenation on SiO2 up to the formation of phthalimide derivatives. (C) 1999 Elsevier Science S.A. All rights reserved.
Asymmetrical induction in the synthesis of bicyclic pyrazolines with a ferrocenyl substituent has been studied. A relatively high diastereomeric selectivity in the 'chiral-center-by-a-chiral-center' induction of the 1,2-type has been observed. Molecular geometry of a cis-diastereomer of 1-acetyl-9-ferrocenyl-4-ferrocenylmethylene-1,2-diazabicyclo[4.3.0]non-2-ene has been established. Bicyclic 2-pyrazolines having conjugated ferrocenylmethylene fragments interact with azodicarboxylic acid N-phenylimide to form diene and monoene adducts. (C) 1999 Elsevier Science S.A. All rights reserved.