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|Title:||The endocyclic restriction test: (I) Determination of reaction pathways for the nucleophilic substitution at phosphorus by carbon. (II) Exploration of the reaction pathway of nucleophilic substitution at an oxenoid oxygen by carbon|
|Author(s):||Tollefson, Michael Brent|
|Doctoral Committee Chair(s):||Beak, Peter|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Double labeling has been used in conjuction with the endocyclic restriction test to show that transfers of phosphorus from oxygen to carbon in the conversions of 45 to 46, of 120 to 126, of 121 to 127 and of 122 to 128 proceed in an intramolecular fashion. The transfers of a chiral phosphorus atom in the conversions of 123 to 129, of 124 to 130 and of 125 to 131 proceed with retention of stereochemistry at phosphorus. These results rule out the classic in-line S$\rm\sb N$2 pathway and the geometrically equivalent in-line addition-elimination pathway for these endocyclic transfers of phosphorus. Initial apical attack followed by pseudorotation and elimination of the apical alkoxy leaving group is suggested for these nucleophilic substitutions at phosphorus.
Application for the endocyclic restriction test to determine the geometry required for nucleophilic substitution at an oxenoid oxygen was attempted. A number of compounds were examined for their ability to react with molecular oxygen to form an oxenoid and carbanion within the same molecule. Oxygen incorporation was observed in a few cases, however, no products which can he definitively ascribed to oxenoid oxygen transfer were observed.
|Rights Information:||Copyright 1996 Tollefson, Michael Brent|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9712461|