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Trimethylsilyl anions: stereospecific deoxygenation of epoxides and trimethylsilyldehalogenation of aryl halides

Citation

Shippey, Michael Allen (1978) Trimethylsilyl anions: stereospecific deoxygenation of epoxides and trimethylsilyldehalogenation of aryl halides. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/g9fx-wb19. https://resolver.caltech.edu/CaltechTHESIS:01232015-153319101

Abstract

I. Trimethylsilylpotassium reacts with epoxides to give olefins with inversion of stereochemistry. The reaction appears to proceed via the potassium β-silyl alkoxide (2) formed from the S_N2 attack of the silyl anion on the epoxide. Subsequent stereospecific synelimination of 2 affords the olefin of inverted stereo-chemistry. The reaction is convenient and preparatively useful.

The byproduct of the reaction, potassium trimethylsilanolate (17), effectively cleaves hexamethyldisilane to yield trimethylsilylpotassium. Since the latter reagent is generated and reacted in situ with epoxides, the overall reaction can be carried out with less than one equivalent of potassium methoxide.

II. The reaction of aryl halides with trimethylsilyl anions in HMPT provides good yields of aryltrimethylsilanes, useful synthetic intermediates. The choice of metal cation is unimportant. Chlorides and bromides give high yields of silylated products, while iodides give lower yields, with correspondingly increased amounts of reduced products. Arylammonium and arylphosphonium salts also undergo the reaction.

We have permissive evidence for the reaction proceeding via both aryl radical and aryl anion intermediates.

III. Trimethylsilyl and trimethylstannyl methoxycarbene complexes of chromium and tungsten have been prepared. One of these, (CO)_5WC(OMe)SnMe_3, reacts with norbornene at 80° to afford a new olefin polymer. Efforts to effect the alpha-elimination of the nonmetallic carbene ligands have not yet been successful. Reactions of these carbene complexes with acetone have been investigated.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Dervan, Peter B.
Thesis Committee:
  • Unknown, Unknown
Defense Date:23 January 1978
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
CaltechUNSPECIFIED
Record Number:CaltechTHESIS:01232015-153319101
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:01232015-153319101
DOI:10.7907/g9fx-wb19
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8759
Collection:CaltechTHESIS
Deposited By: Bianca Rios
Deposited On:23 Jan 2015 23:52
Last Modified:16 Apr 2021 22:16

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