Artur Ulikowski and Chandan Kumar

Artur Ulikowski

Title: The activation of amide carbonyls towards nucleophilic attack – mechanisms and synthetic applications

Artur Ulikowski is visiting from Warsaw. Abstract below.

Chandan Kumar

Title: Approximative Kohn-Sham Response Theory: using Density-fitting and the Auxiliary-Density-Matrix Method

Abstract below.

 

Recordings of both presentations: 480p720p1080p

This is a joint seminar between Oslo and Tromsø in room V205 (Oslo) and ROOM #1.441 (LEVEL 4) Teorifagbygget, House 1 (Tromsø).

The seminars alternate beetween our two Universities and is broadcasted by video to the other place.

Artur Ulikowski abstract: Amides have historically been considered an unreactive, robust moiety. Lately, a number of methods for their selective activation have emerged, elevating the role of the amide group from a synthetic endpoint to a viable handle for the modification of organic compounds. These include activation by triflic anhydride,[1] activation by stoichiometric organometallic compounds,[2] and catalytic organometallic activation.[3] One of the most versatile strategies in amide modification is the use of the Schwartz’s reagent. This zirconium complex has proved to reductively activate amide groups in a mild, chemoselective manner.[2] To date, a range of uses for the Schwartz’s reagent-mediated reduction- addition to amide groups have been proposed, including the functionalization of sugar-derived amides,[4a] the synthesis of bicyclic nitrogenous alkaloids,[4b] the divergent synthesis of 2,3-disubstituted indoles,[5] and accessing compounds of limited availability by the activation of readily available amides. 

The mechanisms of the amide activation processes will be discussed, including computational evidence due to us and other groups,[6] and currently unresolved issues will be highlighted. In addition, the synthetic applications of the discussed transformation will be detailed.

[1] See: G. Pelletier, W. S. Bechara, A. B. Charette, J. Am. Chem. Soc., 2010, 132, 12817.
[2] See: J. T. Spletstoser, J. M. White, A. R. Tunoori, G. I. Georg, J. Am. Chem. Soc., 2007, 129, 3408.
[3] See: C. Cheng, M. Brookhart, J. Am. Chem. Soc., 2012, 134, 11304; F. Tinnis, A. Volkov, T. Slagbrand, H. Adolfsson, Angew. Chem. Int. Ed., 2016, 55, 4562
[4] (a) P. Szcześniak, E. Maziarz, S. Stecko, B. Furman, J. Org. Chem. 2015; 80, 3621; (b) P. Szcześniak, S. Stecko, E. Maziarz, O. Staszewska-Krajewska, B. Furman, J. Org. Chem. 2014, 79, 10487
[5] A. Ulikowski, B. Furman, Org. Lett. 2016, 18, 149.
[6] Schwartz’s reagent-mediated reduction mechanism: J. Wang, H. Xu, H. Gao, C.-Y. Su, C. Zhao, D. L. Phillips, Organometallics 2010, 29, 42. 

 

 

Chandan Kumar abstract: The aim of our work is to investigate the accuracy of the density fitting and the auxuliary-density-matrix-method (ADMM) approximations for linear response and quadratic response. A systematic study on accuracy for the approximations against pcseg-n (n=1,2,3,4) and aug-pcseg (n=1,2,3,4) basis sets is carried out using LSDalton. We show preliminary results for the current implementation. The ADMM results are computationally economical for larger basis-sets without losing significant accuracy. The Density-fitting method performs as well as the unapproximated method. 

Published Jan. 13, 2017 12:58 PM - Last modified Jan. 24, 2017 11:52 AM