Eric C. Hansen
University of Wisconsin-Madison
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Eric C. Hansen.
Organic Letters | 2014
Zhihui Peng; John W. Wong; Eric C. Hansen; Angela L. A. Puchlopek-Dermenci; Hugh J. Clarke
A concise, asymmetric synthesis of a smoothened receptor inhibitor (1) is described. The synthesis features an enzymatic transamination with concurrent dynamic kinetic resolution (DKR) of a 4-piperidone (4) to establish the two stereogenic centers required in a single step. This efficient reaction affords the desired anti amine (3) in >10:1 dr and >99% ee. The title compound is prepared in only five steps with 40% overall yield.
Nature Chemistry | 2016
Eric C. Hansen; Dylan J. Pedro; Alexander C. Wotal; Nicholas J. Gower; Jade D. Nelson; Stephane Caron; Daniel J. Weix
Ligands are essential for controlling the reactivity and selectivity of transition metal-catalyzed reactions. Access to large phosphine ligand libraries has become an essential tool for the application of metal-catalyzed reactions industrially, but these existing libraries are not well suited to new catalytic methods based on non-precious metals (i.e., Ni, Cu, Fe). The development of the requisite nitrogen- and oxygen-based ligand libraries lags far behind phosphines and the development of new libraries is anticipated to be time consuming. Here we show that this process can be dramatically accelerated by mining a typical pharmaceutical compound library that is rich in heterocycles for new ligands. Using this approach, we were able to screen a structurally diverse set of compounds with minimal synthetic effort and identify several new ligand classes for nickel-catalyzed cross-electrophile coupling. These new ligands gave improved yields for challenging cross-couplings of pharmaceutically relevant substrates compared to previously published ligands.
Organic Letters | 2017
Robert J. Perkins; Dylan J. Pedro; Eric C. Hansen
A constant-current electrochemical method for reducing catalytic nickel complexes in sp2-sp3 cross-electrophile coupling reactions has been developed. The electrochemical reduction provides reliable nickel catalyst activation and turnover and offers a tunable parameter for reaction optimization, in contrast to more standard activated metal powder reductants. The electrochemical reactions give yields (i.e., 51-86%) and selectivities as high or superior to those using metal powder reductants and provide access to a wider substrate scope.
Journal of Organic Chemistry | 2009
Ronald L. Blankespoor; Peter J. Boldenow; Eric C. Hansen; Jeffrey M. Kallemeyn; Andrew G. Lohse; David M. Rubush; Derek Vrieze
Photolysis of 1-(3-alkynoxy)-9,10-anthraquinones in deoxygenated methanol leads to moderate yields (35-45%) of 3-alkynals along with the unexpected formation of diacetals. Reaction of these 3-alkynals with Grignard and Wittig reagents occurs nearly quantitatively without rearrangement to their 2,3-dienal isomers.
Journal of Organic Chemistry | 2017
Eric C. Hansen; Changfeng Li; Sihang Yang; Dylan J. Pedro; Daniel J. Weix
Despite their importance, the synthesis of alkylated heterocycles from the cross-coupling of Lewis basic nitrogen heteroaryl halides with alkyl halides remains a challenge. We report here a general solution to this challenge enabled by a new collection of ligands based around 2-pyridyl-N-cyanocarboxamidine and 2-pyridylcarboxamidine cores. Both primary and secondary alkyl halides can be coupled with 2-, 3-, and 4-pyridyl halides as well as other more complex heterocycles in generally good yields (41 examples, 69% ave yield).
Accounts of Chemical Research | 2006
Eric C. Hansen; Daesung Lee
Journal of the American Chemical Society | 2004
Eric C. Hansen; Daesung Lee
Organic Letters | 2004
Eric C. Hansen; Daesung Lee
Journal of the American Chemical Society | 2003
Eric C. Hansen; Daesung Lee
Journal of the American Chemical Society | 2006
Eric C. Hansen; Daesung Lee