Nu14Mig · Generation and Application of Nucleophilic Allylmetal Species by Catalytic 1,4-Metal Migration

Generation and Application of Nucleophilic Allylmetal Species by Catalytic 1,4-Metal Migration

"""Allylmetal species"" are versatile synthetic intermediates in chemistry, which, in their simplest form, are composed of a metal atom bonded to a three-carbon fragment (which also contains a carbon-carbon double bond). Allylmetal species are used in a wide range of reactions to produce numerous important chemical building blocks. In the Host Laboratory, a new method to access allylmetal species was discovered, which involves an addition to a carbon-carbon triple bond to give one organometallic intermediate. The metal in this intermediate then undergoes migration to another position four carbon atoms away. Overall, this migration is called ""1,4-migration"". In the original discovery, rhodium was used as the metal, and the resulting allylrhodium species was used to react with another group in the same molecule to form a cyclic compound. The advantage of this method for producing allylmetal species is that the chemical precursors used are relatively simple, which avoids the need to prepare more complex, more highly functionalized precursors that might otherwise be required using more conventional methods. The original objectives of this project were to: (a) Define the scope and limitations of this method in producing a wide range of cyclic compounds. (b) Develop variants of these reactions that are able to give products selectively as a single enantiomer (which is defined as a non-superimposable mirror-image form). The ability to produce compounds as single enantiomers is very important because the exact function of compounds within biological systems (e.g. if the compounds are to be used as medicines) often depends upon which mirror image they exist in. Ultimately, work in this project was not successful in the original area of study, but in a related area involving the generation of sulfur-based reactive species by visible light in conjunction with an iridium catalyst (Scheme 1). This new method was successful in producing a range of cyclic products in good yields under mild reaction conditions, and at the time of writing, this work is being finished up for publication. "

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