I. Enantioselective metallophosphite-catalyzed aza-benzoin reaction between acyl silanes and nitrones II. Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions and kinetic resolution of resultant alpha-silyloxyketones III. Bis-functionalization of glyoxylate for the synthesis of fully substituted glycolic acids

Public Deposited
Analytics

Downloadable Content

Download PDF
Request Version for Screen Reader
Alternate title
  • Enantioselective metallophosphite-catalyzed aza-benzoin reaction between acyl silanes and nitrones
Last Modified
  • March 21, 2019
Creator
  • Tarr, James Christopher
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • I. Enantioselective Metallophosphite-Catalyzed Aza-Benzoin Reaction Between Acyl Silanes and Nitrones The asymmetric C-acylation of nitrones was developed. TADDOL-derived metallophosphites catalyze the enantioselective addition of acyl silanes to nitrone electrophiles. The product alpha-N-silyloxyamino ketones were obtained in 36-94% yield and greater than 95:5 er. The methodology is scalable, as the yield and er of the products were essentially constant as the scale of the reaction was increased over three orders of magnitude. The products can be further elaborated by reduction of the N-O bond and ketone functionality with negligible loss of optical purity. The nitrone oxygen is essential in facilitating the silyl transfer necessary for catalyst turnover. This reaction constitutes the first example of C-acylation of nitrones and the most highly enantioselective methodology to date for the addition of acyl anion equivalents to azomethine electrophiles. II. Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant alpha-Silyloxyketones An intermolecular cyanide-catalyzed coupling of acyl silanes and ketones has been developed. The reaction scope encompasses alkyl and aryl acyl silanes and aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, and alkynyl-alkyl ketones. In cyclic systems, good to excellent diastereocontrol is observed for equatorial attack. The reaction conditions can be tuned so that either the Felkin-Ahn or chelation-controlled product is obtained when acyclic protected alpha-hydroxyketones are employed. The resultant alpha-silyloxyketones can be resolved with selectivity factors ranging from 10 to 15 via CBS reduction. III. Bis-Functionalization of Glyoxylate for the Synthesis of Fully Substituted Glycolic Acids Current progress towards the development of ethyl glyoxylate as a conjunctive reagent in the three component coupling between ethyl glyoxylate, a nucleophile, and an electrophile is described. The addition of unactivated arene and alkene nucleophiles followed by one-pot electrophilic trapping with aldehydes, Michael acceptors, and ketones has been demonstrated.
Date of publication
DOI
Resource type
Rights statement
  • In Copyright
Note
  • "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry."
Advisor
  • Johnson, Jeffrey
Language
Publisher
Place of publication
  • Chapel Hill, NC
Access right
  • Open access
Date uploaded
  • March 18, 2013

Relations

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details Enantioselective metallophosphite-catalyzed aza-benzoin reaction between acyl silanes and nitrones 2019-04-15 Public Download