Hammett studies of enantiocontrol by PHOX ligands in Pd-catalyzed allylic substitution reactions

Organic Letters

Volumn 5, Issue 13, 2003, Pages 2279-2282

  Constantine, Ryan N ^a   Kim, Naomi ^a   Bunt, Richard C ^a  

^a MIDDLEBURY COLLEGE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALLYL COMPOUND; BENZYLAMINE; LIGAND; MALONIC ACID DERIVATIVE; OXAZOLINE DERIVATIVE; PALLADIUM; PHOSPHINOOXAZOLINE; PHOSPHORUS DERIVATIVE; UNCLASSIFIED DRUG;

ALKYLATION; AMINATION; ARTICLE; CATALYST; ENANTIOSELECTIVITY; MOLECULAR INTERACTION; PROTON NUCLEAR MAGNETIC RESONANCE; STEREOCHEMISTRY; SYNTHESIS;

EID: 0141741604     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol034610q     Document Type: Article

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27. See Supporting Information for full experimental details of palladium-catalyzed allylic-alkylations and aminations of 1a,b.
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31. The raw ee data for the dimethyl malonate alkylation of 1a to give 2a was taken from ref 12. Those authors did not undertake the formal Hammett analysis shown here, nor are these interpretations and conclusions about functioning of ligand 6 necessarily supported by those authors.
32. Since 2a and 2b have opposite (R/S) configurations, the enantiomeric ratio (er) is defined here as the relative amount of the major enantiomer divided by the relative amount of the minor enantiomer (e.g., 80% ee gives an er of 9.0).
33. The er reflects the net ratio of rates of formation of the (R) and (S) products through the four pathways shown in Figure 2.
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35. 2 = 0.91 it is not clear that better fits should be expected.
36. This explanation could avoid any involvement of nucleophilic addition trans to nitrogen.
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38. The difference between 89.3% ee and 93.4% ee corresponds to a ΔG of 0.30 kcal/mol, while the difference between 16.4% ee and 66.6% ee corresponds to a ΔG of 0.75 kcal/mol.