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Novel Approaches to Phosphorus-containing Heterocycles and Cumulenes
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Fast development in all areas of life and science over the last 50 years demands versatile, energy efficient and cheap materials with specific but easily tuneable properties which can be used for example in organic light emitting diodes (OLEDs), thin-film transistors, photovoltaic cells, etc. This thesis is devoted to the development of novel synthetic approaches to molecules with potential applications in the field of molecular electronics.  The acquisition of a detailed mechanistic understanding of the newly developed reactions is central to the work presented in this thesis.

The first chapter is dedicated to the development of a new procedure for the preparation of phospha-Wittig-Horner (pWH) reagents, i.e. a reagents that has been known to convert carbonyl compounds into compounds with P=C double bonds. Each step of the synthetic sequence, i.e. preparation of the starting P,P-dichlorophosphines, their phosphorylation using the Michaelis-Arbuzov protocol, coordination to the metal centre and final hydrolysis, are presented in detail. A possible route to uncoordinated pWH reagents is also discussed.

The second chapter focuses on the reactivity of the pWH reagents with acetone under different reaction conditions. The results show how changes in the ratio of starting material vs. base as well as reaction time or structure of the pWH reagent can influence the reaction outcome and the stability of the obtained products. The possibility to prepare unusual phosphaalkenes with unsaturated P-substituents is presented.

The third chapter of the thesis is dedicated to the reactivity of pWH reagents towards symmetric and asymmetric ketones which contain one or two acetylene units. The proposed mechanisms of the reactions are studied by means of in situ FTIR spectroscopy as well as theoretical calculations. Physical-chemical properties of oxaphospholes, cumulenes and bisphospholes are presented.

The last chapter is dedicated to reactivity studies of pWH reagents towards ketenes, and the exploration of a reliable route to 1-phosphaallenes. Detailed mechanistic studies of the pWH reaction that are based on the isolation and crystallographic characterization of unique reaction intermediates are presented. The reactivity of phosphaallenes towards nucleophiles such as water and methanol are examined.

In summary, this thesis presents synthetic routes to novel phosphorus-containing molecules, together with detailed studies of the reaction mechanisms of the observed transformations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. , 70 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1049
Keyword [en]
phosphorus, phosphole, oxaphosphole, cumulene, phospha-Wittig-Horner reagent, molecular electronics
National Category
Organic Chemistry
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-198813ISBN: 978-91-554-8683-9 (print)OAI: oai:DiVA.org:uu-198813DiVA: diva2:618185
Public defence
2013-06-14, Å2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2013-05-23 Created: 2013-04-25 Last updated: 2013-08-30Bibliographically approved
List of papers
1. Revisiting the Phospha-Wittig - Horner Reaction
Open this publication in new window or tab >>Revisiting the Phospha-Wittig - Horner Reaction
2012 (English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 31, no 3, 1118-1126 p.Article in journal (Refereed) Published
Abstract [en]

P,P-Dichlorophosphines 2a-c (RPCl2, R = Ph (a), t-Bu (b), 2,4,6-Me3Ph (c)) and P,P-dibromophosphines 4d,e (RPBr2, R = (i-Pr)(3)SiC C (d) and H2C=CH (e)) react with triethylphosphite under Michaelis-Arbuzov conditions to give phosphinodiphosphonates 3a-e in quantitative yields. After complexation to W(CO)(5) and treatment with CH3ONa, phospha-Wittig-Horner reagents 9a,b are obtained on a multigram scale in good overall yield. Phospha-Wittig-Horner reagents with unsaturated, substituents at P-III (10d,e) can be prepared in analogous procedures; however, their prevail in an unusual ylide form that allows conjugation between the lone pair and the acetylene and vinyl pi-systems, respectively. Phosphinophosphonate 9a has been characterized by X-ray crystallography and is shown to react smoothly with acetone within minutes. The resulting W(CO)(5)-coordinated phosphaalkene is shown to dimerize to a 1,2-diphosphitane or to undergo a 1,3-proton shift depending on the reaction conditions. In addition, a one-pot synthetic sequence starting from W(CO)(5)-coordinated phosphinodiphosphonates 5d,e has been developed to engage compounds with vinyl and acetylene substituents in phospha-Wittig-Horner reactions.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-170346 (URN)10.1021/om201158k (DOI)000300116100046 ()
Available from: 2012-03-12 Created: 2012-03-12 Last updated: 2017-12-07Bibliographically approved
2. Cascade Reactions Forming Highly Substituted, Conjugated Phospholes and 1,2-Oxaphospholes
Open this publication in new window or tab >>Cascade Reactions Forming Highly Substituted, Conjugated Phospholes and 1,2-Oxaphospholes
2012 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 51, no 31, 7776-7780 p.Article in journal (Refereed) Published
Abstract [en]

The reaction of a phospha-Wittig–Horner reagent with diacetylenic ketones (see scheme) results in a cascade of reactions that can lead to both an oxaphosphole-terminated cumulene system and an alkene-bridged bis-phosphole. The reaction outcome is determined by the nature of the acetylene termini, with phenyl groups stabilizing a carbene intermediate that dimerizes to give the bis-phosphole product.

Keyword
acetylenes, conjugation, cumulenes, phospha-Wittig, reaction mechanisms
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-182042 (URN)10.1002/anie.201202153 (DOI)000306757900029 ()
Available from: 2012-10-05 Created: 2012-10-02 Last updated: 2017-12-07Bibliographically approved
3. Phosphorus Heterocylces from Phosphinophosphonates and α,β-Unsaturated Ketones
Open this publication in new window or tab >>Phosphorus Heterocylces from Phosphinophosphonates and α,β-Unsaturated Ketones
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-198753 (URN)
Available from: 2013-04-25 Created: 2013-04-24 Last updated: 2013-08-30
4. Mechanism of the Phospha-Wittig-Horner Reaction
Open this publication in new window or tab >>Mechanism of the Phospha-Wittig-Horner Reaction
2013 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 25, 6484-6487 p.Article in journal (Refereed) Published
Keyword
ketenes; phosphaallenes; phospha-Wittig-Horner reaction; reaction mechanisms
National Category
Organic Chemistry Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-198754 (URN)10.1002/anie.201301469 (DOI)000320378800024 ()
Available from: 2013-04-25 Created: 2013-04-24 Last updated: 2017-12-06Bibliographically approved

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