Principal Component Analysis on the effect of nucleophiles on the reactivity of α-acylenaminoketones

This report shows the importance of Principal Component Analysis for grouping types of products observed when α-acylenaminoketones K1–K3 react with four substituted hydrazine nucleophiles in five organic solvents. The reactions were carried out with the goal of obtaining substituted pyrazoles and determining which of the carbonyls would preferentially be attacked by the nucleophile. The reaction products were submitted to GC-MS analysis and the results were subjected to Principal Component Analysis (PCA). The data set was separated in four groups (scores). The deacetylated pyrazoles P5 were separated from the other pyrazoles by the first principal component PC1. The second principal component PC2 separated the pyrazoles P4, derived from nucleophilic attack on the acetyl carbonyl group, from the pyrazoles P6, derived from nucleophilic attack on the carbonyl bonded to the more bulky group R (loadings analysis). The simultaneous analysis of the scores-loadings shows the relationship between the mechanisms (types of reaction products-loadings) and the reaction conditions (solvent, nucleophile). Frontier orbital considerations were also included to complete the analysis.