Radical cation cyclization of cyclopropyl silyl ethers induced by PET: synthetic applications for the construction of polycyclic compounds and Photoacylation of 1,4-naphthoquinones [Elektronische Ressource] : a concise access to the biologically active quinonoid compounds / by Prashant Ankushrao Waske

Prashant Waske

Informations

• Publié par: universitat_bielefeld
• Publié le: 01 janvier 2006
• Nombre de lectures: 37
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Radical Cation Cyclization of Cyclopropyl Silyl Ethers Induced by PET
Synthetic Applications for the Construction of Polycyclic Compounds
and
Photoacylation of 1,4-Naphthoquinones
A Concise Access to the Biologically Active Quinonoid Compounds









Dissertation
Submitted to the Department of Chemistry
University of Bielefeld
In partial fulfillment of requirements for the degree of a
Doctor rerum naturalium
(Doctor of Philosophy)



by
Prashant Ankushrao Waske, M. Sc.,
Bielefeld 2006










Radical Cation Cyclization of Cyclopropyl Silyl Ethers Induced by PET
Synthetic Applications for the Construction of Polycyclic Compounds
and
Photoacylation of 1,4-Naphthoquinones
A Concise Access to the Biologically Active Quinonoid Compounds









Dissertation
Submitted to the Department of Chemistry
University of Bielefeld
In partial fulfillment of requirements for the degree of a
Doctor rerum naturalium
(Doctor of Philosophy)



by
Prashant Ankushrao Waske, M. Sc.,
Bielefeld 2006




















Dissertation advisor: Prof. Dr. Jochen Mattay

Dissertation co-referee: Prof. Dr. Dietmar Kuck

Date of oral examination: 03.05.2006















Dedicated to my Beloved Parents






The research work presented here is accomplished under the guidance of

Professor Dr. Jochen Mattay

at the Department of Chemistry, Organic Chemistry-I, University of Bielefeld, Germany,

during May 2001 until December 2005.


Aknowledgement

I would like to take this opportunity to express my gratitude to those peoples who made my
stay at Bielefeld pleasant and memorable.
First of all I would like to thank my research advisor Prof. Jochen Mattay for giving me
opportunity to work in his group on a very interesting research topic, “synthetic aspects of
photochemistry”. I am very grateful to him for his valuable support, continuous enthusiasm
and encouragement for this work. He has provided many opportunities to increase my abilities
as a researcher and responsibilities as a group member.
My most sincere thanks to Prof. Dr. Dietmar Kuck, for his outstanding cooperation,
numerous scientific discussions, helpful suggestions and his valuable reference.
I would like to thank Mrs. Arja Gaestel for her continuous help in official matters as
well as friendly discussions.
I am very grateful to Prof. Dr. Norbert Sewald for giving his valuable reference.
I would like to thank all the AK Mattay past and present group members for helping me
to carry out research and the pleasant working environment. In particular, Dr. Jens Bunte and
Dr. Heiko Rinderhagen for making me familiar with the photochemistry. I also thank to Dr.
Michael Oelgemoeller (Lecturer, Dublin City University) and Dr. Christian Schiel for helpful
discussions and suggestions about the quinone photochemistry.
I also thank our Photochemistry team, especially to Dr. Juliane Grota for helpful
discussions about the mechanistic photochemistry and giving the responsibility to maintain
our GC instruments and to Dr. Nikolay Tzvetkov for his kind help as a translator during my
beginning days and also I am thankful to him for his friendship.
My special thanks to senior colleagues Dr. Ceno Agena, Dr. Philip Schmold, Dr. Lars
Christmann, Dr. Lars Ulmer and Dr. Marco Hering for support and help in the begining.
Also my special thanks to Dr. Björn Decker, Dr. Michael Schiendorfer, Mr. Christian
Schäfer, Mr. Björn Schnatwinkel, Mr. Ion Stoll (for nice calendars), Mr. Jörg Srübe and Dr.
Michael Klaes, my wonderful colleagues for their fun-filled working environment, interesting
discussions and speaking with me in ‘german’.
I would like to thank Mr. Olaf Barton my colleague as well as caption our basket ball
team, for encouraging me to join the basket ball team and many chemistry related discussions.
I also thank Mr. Mirco Beining for discussing spiro-chemistry related problems as well as
many general discussions.
My special thanks to Mr. Dieter Barth and Mr. Thomas Geisler for their technical help
on the daily basis and for maintaining the solvent distillation up to date.
I would like to express my deep gratitude to Mr. Peter Mester for carrying out countless
1D and 2D NMR measurements. Without his help it would have not been possible to identify
the chemical structures of new substances.
Dr. Matthias Letzel, I thank him for measuring crucial MS and exact mass analysis of
organic compounds in a very short time, which was very helpful for the identification of new
photoproducts. I am thankful to Mr. Eckard Westermayer for several MS measurements.
I would also like to thank Mrs. Beate Neumann and Dr. Hans-Georg Stammler for
single crystal X-ray analysis.
My special thanks to Dr. Ulrich Neuert for his assistance in Computer, Server, Software
and Printer (especially Kyocera FS-1750 duplex) related problems.
I am also grateful to all the OC-II Praktikants who worked really hard to finish the given
synthetic projects.
I am very thankful to all my Indian friends in Germany, especially Dr. Santosh Bhor,
Dr. Vivek Khedkar, Dr. Anup Jawalekar and Dr. Khalil Shaikh for their friendship, moral
support, constant encouragement, chemistry and non-chemistry related discussions.
I am thankful to Dr. Gokulakannan, (Dr.) Gomathi Gandhi, Mr. Dhananjaya, Mr.
Parmeshwaranji, Mrs. Lakshmiji and their children for making my stay at Bielefeld pleasant. I
am also thankful to our other Indian students in Universität Bielefeld for making memorable
round table discussions in Uni. Mensa during lunch time.
Once again I thank Mr. Mirco Beining, Mr. Björn Schnatwinkel and Dr. Nikolay
Tzvetkov for their patience in reading this thesis and helpful suggestions.
I would also like to express by deepest gratitude to my brother Mr. Shashikant
(Research Scientist, Ranbaxy Ltd.) for his constant support encouragement, giving tips and
tricks for using analytical and preparative HPLC. His important suggestions made the
purification of structurally novel compounds possible via HPLC. I am also thankful to
Pramodini Vahini for promoting me as a ‘Bhau’ to ‘Kaka’ by giving birth to Shreya (Siddhi). I
also thank to Shubhangee (Akka) my sister for the constant encouragement and support.
I wish to thank my beloved parents, father (Papa) and my mother (Aie) for their
blessings, constant support, love, and encouragements.
Last but not least, I would like to thank Universität Bielefeld, the Volkswagen-stiftung
and Landes Nordrhein-Westfalen for the financial support.





Table of Contents I
1 Introduction .....................................................................................................................1
2 Objectives ........................................................................................................................9
3 Introduction to the Electron Transfer (ET)....................................................................11
3.1 General Introduction......................................................................................................11
3.2 Photoinduced Electron Transfer (PET) .........................................................................14
3.2.1 Rates of electron transfer and quantum efficiency of photoinduced electron
transfer process17
3.2.2 Sensitizers and co-sensitizers.................................................................................18
3.2.3 Generation of radical anions via photoinduced electron transfer ..........................20
3.2.4 Generation of radical cations via photoinduced electron transfer reactions of silyl
enol ethers. .............................................................................................................25
3.2.5 Generation of radical cations via oxidative PET of olefins ...................................27
3.2.6 Generation of radical cation from cyclopropyl silyl ether via photoinduced
electron transfer .....................................................................................................29
3.2.7 Generation of radical cations using cyclopropyl amines via PET .........................30
4 Results and Discussion ..................................................................................................33
4.1 Photoinduced Electron Transfer Reactions of Cyclopropyl Silyl Ethers ......................33
4.1.1 Introduction............................................................................................................33
4.1.2 Facile ring opening reaction with FeCl ................................................................33 3
4.1.3 Photoinduced electron transfer reactions of cyclopropanone acetals ....................34
4.1.4 Photoinduced electron transfer reactions of cyclopropyl silyl ethers3