| |
| author |
Josh Trochez
| | title |
Ketone and Alkyl Halide/ Aryl Halide Barbier Coupling Reactions Using Versatile SmI2 - Ni (II) System and External Ligands
| | abstract |
Samarium Diiodide (SmI2) is a single electron reductant with the ability to couple
carbonyls, aldehydes and alkyl halides. SmI2 has been effectively used with NiI2 to carry out
Barbier reactions in the past, which has a similar mechanistic approach as the Nozaki- Hiyama-
Kishi reaction which uses chromium (II) instead of SmI2. This paper first focuses using the
well-known Sm- Barbier coupling reaction to explore the product selectivity of a range of
substrates. Furthermore, this paper investigates the ability for external ligands to stabilize the Ni
(0) intermediate that forms in the Barbier pathway and the effect these have on product
selectivity. Three phosphorus-based ligands and one nitrogen-based ligand were used in this
study, as well as two different Nickel (II) sources. Three different alkyl halide- ketone Barbier
coupling reactions were carried out, with one yielding high Barbier selectivity, while the other
two had decent to low product ratios. Addition of ligands led to a slight increase in product
selectivity with Triphenylphosphine (PPh3), while a decrease in Barbier selectivity with all
others. These results suggest that Ni (0) chemistry must be further studied with other ligands to
determine how it can be stabilized to effectively and continuously carry out the Barbier cycle.
This paper utilizes the Sm- Barbier coupling pathway to investigate ketone and aryl halide as
well as ketone- vinyl halide couplings as we try to provide an alternative to the NHK reaction
which utilizes carcinogen chromium (II) and is used in biomedical synthesis. This paper, for the
first time reports successful ketone and aryl halide (SP2 carbon) coupling using versatile
reductant system SmI2-Ni (II) and external ligand. Reactions with DPPP as the external ligand
saw the highest selectivity for the desired ketone- aryl coupled product, although the side
products were still highly favorable. In the future, other ligands should also be tested to increase
ketone-aryl product selectivity and try to diminish or even eradicate the side products observed
in this reaction. Lastly, a vinyl halide was successfully synthesized in the lab and used to carry
out a coupling reaction with a ketone. For the first time, we report successful vinyl halide- ketone
coupling using SmI2- Ni (II) system as a trace amount was observed when this reaction was
carried out with 4 eq DPPP. These findings are promising as a similar approach can be made for
future ketone and vinyl halide (SP2 carbon) optimization reactions aiming for single product
selectivity to successfully provide an alternative to the NHK reaction.
| | school |
The College of Liberal Arts, Drew University
| | degree |
B.S. (2025)
|
| advisor | Kimberly Choquette |
| full text | JTrochez.pdf |
| |
