Papers by Catharine Larsen
A tandem hydroamination–alkynylation was developed as a unique mode of accessing tetrasubstituted... more A tandem hydroamination–alkynylation was developed as a unique mode of accessing tetrasubstituted propargylic amines. The first equivalent of an alkyne acts as the electrophile in a Markovnikov hydroamination. The resultant ketimine intermediate is attacked by the second equivalent of alkyne in its nucleophilic copper acetylide form. Studies on the role of each component indicate that the overall reaction is first-order in copper, amine, and alkyne. In addition, a tandem hydroamination–hydrovinylation provides for an unprecedented onestep synthesis of a 1-amino-1,3-butadiene from phenylacetylene and morpholine.
ChemInform, 2013
A wide range of natural products and bioactive compounds contain fully substituted carbon centers... more A wide range of natural products and bioactive compounds contain fully substituted carbon centers. To circumvent the difficulty of creating these hindered CÀN bonds in one step, compounds are commonly synthesized and rearrangement induced. A catalytic system capable of overcoming the barrier to the condensation of a ketone and an amine to a ketimine, while leaving a nucleophile able to attack would lead to the direct formation of tetrasubstituted carbon atoms bearing amines. In contrast to the wide array of threecomponent couplings (3CC) of aldehydes by the in situ formation of aldimines, reactions of ketones as electrophiles require an extra step that costs time, energy, and chemicals to produce and purify the ketimine starting material. Dozens of enantioselective additions to ketimines have appeared without examples of the corresponding 3CC in either asymmetric or racemic form. This situation suggests that the direct 3CC of ketones is more difficult to achieve than the asymmetric addition of nucleophiles to preformed ketimines.
Organic Letters, 2007
A highly efficient Cu-catalyzed tandem C-N bond-forming reaction of 1,4-dihalo-1,3-dienes has bee... more A highly efficient Cu-catalyzed tandem C-N bond-forming reaction of 1,4-dihalo-1,3-dienes has been developed. The transformation allows the synthesis of pyrroles and heteroarylpyrroles with a wide variety of functional groups and substitution patterns from readily available precursors.
Journal of the American Chemical Society, 2005
Journal of the American Chemical Society, 2005
The factors controlling the highly alpha-selective C-glycosylation of ribose derivatives were det... more The factors controlling the highly alpha-selective C-glycosylation of ribose derivatives were determined by examining the stereoselective reactions of 18 ribose analogues differing in substitution at C-2, C-3, and C-4. The lowest energy conformers of the intermediate oxocarbenium ions display the C-3 alkoxy group in a pseudoaxial orientation to maximize electrostatic effects. To a lesser extent, the C-2 substituent prefers a pseudoequatorial position, and the alkyl group at C-4 has little influence on conformational preferences. In all cases, the product was formed by stereoelectronically preferred inside attack on the lowest energy conformer.
Journal of the American Chemical Society, 1999
... Brian H. Ridgway, Jared T. Shaw, and KA Woerpel*. Department of Chemistry, University of Cali... more ... Brian H. Ridgway, Jared T. Shaw, and KA Woerpel*. Department of Chemistry, University of California Irvine, California 92697-2025. J. Am. Chem. Soc. ... Jonathan S. Rhoad, Brett A. Cagg and Patrick W. Carver. The Journal of Physical Chemistry A 2010 114 (15), 5180-5186. ...
Green Chem., 2015
Copper(II) chloride catalyzes the three-component coupling of cyclohexanone, amines, and alkynes ... more Copper(II) chloride catalyzes the three-component coupling of cyclohexanone, amines, and alkynes to produce tetrasubstituted propargylamines. As a wide range of substrates react without solvent, excess starting material, or other additives, water is the sole by-product. Studies demonstrate that this reaction is first order in copper, cyclohexanone, amine, and alkyne. These mild conditions allow for the first direct, catalytic synthesis of silyl-protected tetrasubstituted propargylamines.
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Papers by Catharine Larsen