Type of Document Dissertation Author Lawrence, Steve O URN etd-03312009-003522 Title The Syntheses of Methyl Jasmonate and Analogs of Alpha–Methylene–Gamma–Butyrolactone Utilizing Titanium Mediated Cyclocarbonylation Degree Doctor of Philosophy (Ph.D.) Department Chemistry Advisory Committee
Advisor Name Title William Crowe Committee Chair Graca Vicente Committee Member Jayne Garno Committee Member William Daly Committee Member Kirsten Prufer Dean's Representative Keywords
- hetero Pauson Khand
- Methyl Jasmonate
- Natural Products
Date of Defense 2009-02-18 Availability unrestricted AbstractFrom its humble beginnings as a novel carbon–carbon bond forming reaction, the Pauson–Khand reaction has lead to the synthetic development of a variety of natural products.
One particular variation of the Pauson–Khand reaction was called the hetero Pauson–Khand. This reaction differs from the normal Pauson–Khand reaction because the reaction employs an intramolecular titanium mediated cycloaddition using enal and enones instead of alkenes and alkynes functional groups to prepare a variety of natural products. These natural products usually contain a bicyclic cyclopentenone core. Because the new ring contains a hetero atom, the name hetero Pauson–Khand was coined.
Alpha–Methylene–Gamma–Butyrolactones posses a wide range of biological activities. These activities range from antibacterial to anti–inflammatory and make these lactones interesting targets for synthetic groups to produce in labs. In an attempt to expand our knowledge of titanium chemistry, alpha–methylene–gamma–butyrolactones syntheses were investigated using titanium catalyzed hetero Pauson–Khand reaction. Several substituted titanacene metallacycles were produced in good to excellent yields since the carbon monoxide insertion under pressure proved problematic.
Because of its importance to the perfume industry; many synthetic groups have synthesized methyl jasmonate. Methyl jasmonate was synthesized from 3–(tert–Butyl–dimethyl–silanyloxy)–propionaldehyde and 5–Bromo–penta–1,3–diene using the hetero Pauson–Khand reaction in twelve steps. Methyl jasmonate was converted from jasmonic acid in 60 % yield as clear oil.
In an effort to circumvent the problems associated with synthesizing alpha–methylene–gamma–butyrolactones from the hetero Pauson–Khand reaction; isonitrile insertions into allenals and allenones were investigated. If successful, these iminocyclopentanones would have been hydrolyzed to the corresponding alpha–methylene–gamma–butyrolactones. Initial titanacene macrocycles formed, but the desired iminocyclopentanones intermediates were never produced.
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