The present dissertation research is largely focused on the methods to synthesize highly
substituted allene derivatives from alkynes in conjugation with carbonyl-containing functional
groups. A key aspect of this research involves methylcyclopentadienylmanganese dicarbonyl
(MMD), an inexpensive and air-stable organometallic auxiliary linked to alkynyl carbonyls via an
η2-bond. This auxiliary influences bond formation to achieve enhanced stereoselectivity without
itself undergoing any chemical transformation.
Chapter 1 accounts various examples of such transition metal auxiliaries including MMD.
Typically conjugated alkynyl carbonyls do not isomerize to thermodynamically less favored
allenes. However, with the MMD auxiliary in place, alkynyl carbonyl compounds undergo facile
1,3-proton shifts in the presence of a mild base to produce allene isomers. Although allenyl
aldehydes are important building blocks, we note that direct methods to prepare them nonracemically
are not known. Chapter 2 describes the development of a new cinchonine-based phase transfer catalyst to
access non-racemic allenyl aldehydes from MMD-complexed alkynyl aldehydes. With the
manganese auxiliary in place, nonracemic allenyl aldehydes were obtained in a weakly basic
biphasic reaction system via enantioselective protonation conditions.
Chapter 3 describes the second use of the MMD auxiliary to direct nucleophilic addition reactions
to allenyl aldehydes for the preparation of 2,3-allenols diastereoselectively. In the absence of the
MMD auxiliary, nucleophilic reactions to the carbonyl group of axially chiral allenyl aldehydes is
poorly diastereoselective, which is a long-standing problem. We observed that, in addition to
leading to non-racemic allenyl aldehydes, the MMD auxiliary could also be used to improve
diastereoselectivity in carbonyl additions due to its proximal position on the 2,3-bond of the allenyl
aldehyde.
Chapter 4 describes the use of allenyl esters as metathesis quenching agents. It was observed
that the addition of an allenyl ester after a metathesis reaction was complete; facilitate the
removal of most ruthenium metal impurities using simple silica chromatographic purification. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
| Identifer | oai:union.ndltd.org:fau.edu/oai:fau.digital.flvc.org:fau_38052 |
| Contributors | Roy, Animesh (author), Lepore, Salvatore D. (Thesis advisor), Florida Atlantic University (Degree grantor), Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry |
| Publisher | Florida Atlantic University |
| Source Sets | Florida Atlantic University |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Format | 171 p., application/pdf |
| Rights | Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder., http://rightsstatements.org/vocab/InC/1.0/ |
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