University of Illinois Urbana-Champaign

Stereoselective alkylations and rearrangements of chiral phosphonic and phosphinic acid derivatives

Dorow, Roberta L.

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Description

Title
Stereoselective alkylations and rearrangements of chiral phosphonic and phosphinic acid derivatives
Author(s)
Dorow, Roberta L.
Issue Date
1990
Doctoral Committee Chair(s)
Denmark, Scott E.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Organic
Language
eng
Abstract
  • The stereochemical course of carbon migration from phosphorus to nitrogen and oxygen were investigated. Optically active ($\geq$99.9% e.e.) phosphonic and phosphinic azides were prepared and photolyzed in methanol to effect the phosphorus analogues of the carbonyl-Curtius rearrangement. These studies showed that carbon migration in the phosphinoyl-Curtius rearrangement proceeds with 99% net retention of configuration while the migration in the first example of the phosphonoyl-Curtius rearrangement occurs with 99.4% net retention of configuration.
  • The stereoselectivity in the alkylation reactions of various chiral phosphorus-stabilized benzylic carbanions was also examined. Both racemic and scalemic 2-benzyl-1,3,2-oxazaphosphorinane-2-oxides were employed. The effects of solvent, base, additive, and electrophile were studied. The diastereoselectivity of alkylation is dependent on the phosphorus-stabilized carbanion which is used, but high diastereoselectivity (98:2-95:5) was realized.
  • Multinuclear NMR spectroscopy was used to gain insight into the solution state structure of both symmetrical and unsymmetrical heterocyclic phosphorus-stabilized benzylic carbanions. The spectral data is consistent with a charge-alternating structure that has a planar anionic carbon. Information about the conformation of the anion as well as the ring form was obtained. Much information about the structure of phosphorus-stabilized carbanions was obtained through X-ray crystallographic studies of the first lithiated phosphonoyl-stabilized carbanion.
Type of Resource
text
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http://hdl.handle.net/2142/20514
Copyright and License Information
Copyright 1990 Dorow, Roberta L.

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