Determination of the relative stereochemistry in flexible systems using NMR parameters

• Grant number: 12/08232-5
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2012
• End date: November 30, 2012
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: Roberto Rittner Neto
• Grantee: Marco Antonio Barbosa Ferreira
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The current project aims to investigate medium and large flexible organic molecules, analyzing the full molecular system in the context of the configurational analysis by theoretical calculations of NMR parameters at DFT (Density Functional Theory) level, and then comparing the experimental and theoretical results using the following comparison methods: "linear correlation", MAE, CMAE, CP3, and DP4. NAMFIS and "Cluster Analysis" methods will be employed in the conformational search step, which deals with a large set of conformers, extracting representative groups and thus reducing the computational cost of the analysis. These strategies can be applied to analyze the antagonistic behavior for ABX spin system of the alpha-methylenic unity in Felkin and anti-Felkin aldol adducts deriving from beta-branched aldehydes and aldehydes lacking beta-branches with methylketones. It will also be investigated how parameters of NMR flexible organic molecules, such as goniotrionin and migrastatin, are affected by the presence of remote stereocenters and conformational boundaries. (AU)