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The Garg Research Group at UCLA

Professor Neil Garg

Professor Neil Garg 


Professor Neil Garg received a B.S. in Chemistry from New York University where he did undergraduate research with Professor Marc Walters. During his undergraduate years, he spent several months in Strasbourg, France while conducting research with Professor Mir Wais Hosseini at Université Louis Pasteur as an NSF REU Fellow.

Garg obtained his Ph.D. in 2005 from the California Institute of Technology under the direction of Professor Brian Stoltz. He then joined Professor Larry Overman’s research laboratory at the University of California, Irvine as an NIH Postdoctoral Scholar. Garg joined the faculty at UCLA in 2007. In 2012, he was promoted to Associate Professor and began serving as Vice Chair for the Department of Chemistry and Biochemistry. In 2013, he was promoted to Full Professor.

Learn More About The Garg Research Group

 

Paraffin–Ni(cod)2 Capsules for Use in Ni-catalyzed Cross-Couplings on the Benchtop

Advantages

• No Glovebox Handling Required
• General use in Ni(cod)2-mediated reactions
• Long-term air and moisture stability


Prof. Garg’s lab is interested in the development of catalytic methodologies to activate amide C–N bonds for subsequent manipulation. Toward this end, they have developed a number of nickel-catalyzed amide activation reactions to access esters, other amides, and ketones from this traditionally inert functional group.

The general use of these methodologies has been fettered by the requirement of glovebox handling of the synthetically important, air sensitive Ni(cod)2 precatalyst. As a means to eliminate glovebox requirements for use of this chemistry, Garg and Co. developed paraffin–Ni(cod)2 capsules that enable the transformations to be performed entirely on the benchtop. The capsules have been demonstrated to work in the aforementioned amide activation reactions as well as a number of other Ni(cod)2-mediated cross-coupling reactions.

These capsules are expected to broaden the use of nickel catalysis in both academia and industry. 

Technical Applications


Molecular Functionalizations using Wax encapsulated Ni(cod)2

Benchtop Delivery of Ni(cod)2 using Paraffin Capsules

A vial containing a magnetic stir bar is flame-dried under reduced pressure, and then allowed to cool under N2. The vial is charged with morpholine (52.4 uL, 0.600 mmol, 1.2 equiv), sulfamate (100.5 mg, 0.500 mmol, 1.0 equiv), anhydrous powdered NaOtBu (72.0 mg, 0.750 mmol, 1.5 equiv), SIPr•HCl (42.7 mg, 0.100 mmol, 20 mol%), and a paraffin capsule containing Ni(cod)2 (13.8 mg, 0.050 mmol, 10 mol%). The vial is flushed with N2, and subsequently 1,4-dioxane (2.5 mL, 0.20 M) is added. The vial is capped with a Teflon-lined screw cap under a flow of N2 and the reaction mixture is stirred at 80°C for 3h. After removing the vial from heat, the reaction mixture is transferred to a 100 mL round bottom flask containing 3.0 g of silica gel with hexanes (6.0 mL) and CH2Cl2 (6.0 mL). The mixture is adsorbed onto the silica gel under reduced pressure and filtered over a plug of silica gel (100 mL of hexanes eluent to remove paraffin, then 100 mL of 1:1 Hexanes:EtOAc eluent). The volatiles are removed under reduced pressure, and the crude residue is purified by preparative thin-layer chromatography (19:1 PhH:EtOAc) to yield amine (78% yield, average of two experiments) as a white solid.1)

Benchtop Delivery of Ni(cod)2 using Paraffin Capsules

A vial is charged with anhydrous powdered K3PO4 (84.8 mg, 0.400 mmol, 2.0 equiv) and a magnetic stir bar. The vial and contents are flame-dried under reduced pressure, and then allowed to cool under N2. The vial is charged with amide substrate (65.8 mg, 0.200 mmol, 1.0 equiv), phenylboronic acid pinacol ester (102.0 mg, 0.500 mmol, 2.5 equiv), and a paraffin capsule containing Ni(cod)2 (2.8 mg, 0.010 mmol, 5 mol%) and SIPr (3.9 mg, 0.010 mmol, 5 mol%). The vial is flushed with N2, and subsequently water (7.2 uL, 0.400 mmol, 2.0 equiv) and toluene (0.20 mL, 1.0 M) are added. The vial is capped with a Teflon-lined screw cap under a flow of N2 and the reaction mixture is stirred vigorously (1,000 rpm) at 50 °C for 18h. After removing the vial from heat, the reaction mixture is transferred to a 100 mL round bottom flask containing 2.0 g of silica gel with hexanes (6.0 mL) and CH2Cl2 (6.0 mL). The mixture is adsorbed onto the silica gel under reduced pressure and filtered over a plug of silica gel (50 mL of hexanes eluent to remove paraffin, then 50 mL of EtOAc eluent). The volatiles are removed under reduced pressure, and the crude residue is purified by preparative thin-layer chromatography (8:1:1 Hexanes:Et2O:CH2Cl2) to yield ketone (82% yield, average of two experiments) as a white solid.1)

References

J.E Dander, N.A. Weires, N.K. Garg, Org. Lett. 2016, 18, 3934.

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