An A value of 3.7 kcal/mole was determined for the (η⁵-cyclopentadienyl) iron (II) dicarbonyl group by variable temperature ¹H NMR spectroscopic studies on cis-4-phenyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane. This is the first determination of the A value of a group with a transition metal directly attached to a cyclohexane ring. The energy of activation (-ΔG‡) for ring inversion of cis-4-phenyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane was calculated to be 9.4 kcal/mol. The stereospecific synthesis of cis- and trans-4-phenyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane, cis- and trans-4-tert-butyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane and the X-ray crystal structure of cis-4-tert-butyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane are reported. The multistep stereospecific synthesis of the redox active adenine analog (S)-ferrocenyl-4-aminopyrimidine is reported. This redox active system will be incorporated into oligonucleotides to study the electron transfer through the molecular π-stack system of DNA in future studies. This synthesis used a chiral metalation to synthesize α-aminoferrocenenitrile. t-Butylcarbamate as the metalation-directing group gave a low yield of the 1,2-disubstituted ferrocene. N,N-diisopropylcarboxamide as the metalation-directing group using a chiral base gave moderate yields of 1,2-disubstituted ferrocene derivatives. However, standard hydrolytic methods failed to hydrolyze the diisopropylamide grouping in these 1,2-disubstituted ferrocene derivatives. A new method was developed to convert the amide functionality of N,N-diisopropylferrocenecarboxamide to ester functionality using Me₃O⁺BF₄⁻, NaOMe and an acidic workup. Unfortunately, when this condition was applied to iodo-N,N-diisopropylferrocenecarboxamide and amino-N,N-diisopropylferrocenecarboxamide, only starting materials and N',N'-dimethylamino-N,N-diisopropylferrocenecarboxamide were obtained, respectively. A chiral acetal as the metalation-directing group was used to give stereoselectively (S)-α-carbomethoxyferrocenecarboxaldehyde after the hydrolysis of the acetal group. The aldehyde was then converted to the nitrile, and the ester group was converted to an amino group to give (S)-α-aminoferrocenenitrile. In a two step sequence, (S)-α-aminoferrocenenitrile was reacted with HC(OMe)₃ and gaseous ammonia to give (S)-α-ferrocenyl-4-aminopyrimidine.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/283985 |
| Date | January 1999 |
| Creators | Stessman, Nhu Y. Tran |
| Contributors | Glass, Richard S. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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