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New Methods for Synthesis of Organic Peroxides and Application Of University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Student Research Projects, Dissertations, and Chemistry, Department of Theses - Chemistry Department Spring 4-2015 New Methods for Synthesis of Organic Peroxides and Application of Peroxide Electrophiles to Synthesis of Functionalized Ethers Shiva Kumar Kyasa University of Nebraska-Lincoln, [email protected] Follow this and additional works at: http://digitalcommons.unl.edu/chemistrydiss Part of the Organic Chemistry Commons Kyasa, Shiva Kumar, "New Methods for Synthesis of Organic Peroxides and Application of Peroxide Electrophiles to Synthesis of Functionalized Ethers" (2015). Student Research Projects, Dissertations, and Theses - Chemistry Department. 51. http://digitalcommons.unl.edu/chemistrydiss/51 This Article is brought to you for free and open access by the Chemistry, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Student Research Projects, Dissertations, and Theses - Chemistry Department by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. NEW METHODS FOR SYNTHESIS OF ORGANIC PEROXIDES AND APPLICATION OF PEROXIDE ELECTROPHILES TO SYNTHESIS OF FUNCTIONALIZED ETHERS by Shiva Kumar Kyasa A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy Major: Chemistry Under the Supervision of Professor Patrick H. Dussault Lincoln, Nebraska March, 2015 NEW METHODS FOR SYNTHESIS OF ORGANIC PEROXIDES AND APPLICATION OF PEROXIDE ELECTROPHILES TO SYNTHESIS OF FUNCTIONALIZED ETHERS Shiva Kumar Kyasa, Ph.D. University of Nebraska, 2015 Adviser: Patrick H. Dussault New Method for Synthesis of Alkyl Hydroperoxides: There are a number of methods reported for synthesis of alkyl hydroperoxides, but most of them suffer either from poor yields or the formation of unwanted side products. I will be discussing new methodology for efficient synthesis of pure samples of 1° and 2° alkyl hydroperoxides via alkylation of readily available cyclododecanone 1,1-dihydroperoxide followed by hydrolysis of the resulting bis peroxyacetals. Peroxide Electrophiles for Synthesis of Functionalized Ethers: Peroxides are underexplored functional groups as precursors for C-O bond formation and ether synthesis. The reactivity of dialkyl peroxides towards organometallics such as alkyl lithium and magnesium reagents is known. However, there has been little application of this reaction to C-O bond formation due to limitations in the reactivity of available reagents for alkoxide transfer. We have studied the reactivity of a variety of dialkyl peroxides, alkyl/silyl peroxides, and monoperoxyacetals towards simple organolithium and organomagnesium reagents and found that thermally stable 2-tetrahydropyranyl peroxides enable efficient and highly selective transfer of 1°, 2° and 3° alkoxide (RO) groups to carbanions to form the corresponding ethers. The method was applied to synthesis of a variety of functionalized ethers, including S,S,O-orthoesters, difluoroethers, mixed O,O-acetals, and cyclopropyl ethers. The observed results are discussed in terms of possible mechanisms for C-O bond formation. i To, My Parents Balaiah & Laxmi and wife Jyothi ii Acknowledgements I am extremely grateful to Prof. Patrick H. Dussault for his guidance for my doctoral research and teaching of organic chemistry in the classroom. I couldn’t go into the depths of organic synthesis and peroxide chemistry without his help. I would like to thank Prof. David B. Berkowitz for reading and suggesting the edits to my dissertation. I would like to thank my committee members Prof. Liangcheng Du, Prof. Li Tan, and Prof. Rebecca Lai. I am very thankful to Dr. Chris Schwartz for useful discussions of my projects at beginning of my Ph.D. I would like to thank Dr. Martha Morton, whenever I have questions about NMR always helpful, Sarah Basiaga teaching IR, GC-MS, TGA-DSC data recording. I also thankful to current and previous colleagues. iii Chapter-1. Reductive amination of hydroperoxy acetals; application of reductive amination in tandem with ozonolysis. Section-1: Introduction. …………………………………………………………..………2 Section-2: Background on peroxyacetal functionalization. …………………….………..3 Section-3: Brief introduction about reductive amination. …………………….………….8 Section-4: Previous reductive amination of peroxyacetals in tandem with alkene cleavage.….……12 Section-5: Synthesis of hydroperoxyacetals/ketals and reduction with Na(OAc)3BH…..13 Section-6: One pot synthesis of amines from hydroperoxy acetals. ………………….....15 Section-7: One pot synthesis of amines from alkenes. ………………………………….17 Section-8: Reductive formation of hydrazides. ………………………………………... 19 Section-9: Conclusions. ………………………………………………………………... 21 Section-10: Experimental section. ......…………………………………………………..21 Section-11: References. …………………………………………………………………22 Chapter-2: A New Synthesis of Alkyl hydroperoxides. Section-1: Background on alkyl hydroperoxide synthetic methods..….………….....…..24 Section-2: 1,1-Dihydroperoxide (DHP) synthesis and use as nucleophiles..………........30 Section-3: Bisperoxyacetals..………………………………………………………....….32 3.1: Synthesis of bisperoxyacetals from 1,1-dihydroperoxides…………..…….….…...,.33 3.2: DHP alkylation using alkyl triflates. …………………………….……..…………...37 Section-4: Alkyl hydroperoxides via hydrolysis of bisperoxy acetals …………. …..…..38 4.1: Studies towards chiral alkyl hydroperoxides ………………....…...………..………43 4.2: Stability studies of bisperoxyacetals …………………….…..…………………..….45 iv Section-5: Experimental procedures. ………………….………………………….…….46 Section-6: References ………………………………….………………………….…….47 Chapter-3: Investigations of factors controlling reactivity of dialkyl peroxides with organometallic species. Section-1: Background on peroxides as electrophiles. ……………….…………...….…50 1.1: Reactions with C-C sigma and pi bonds. ………………….…...…..……….....……51 1.2: Reactions with heteroatom nucleophiles. .………………………….……...….........54 1.3: Lewis acid activated reactions of peroxides and hydroperoxides. ………………….59 Section-2: Background on reaction of peroxides with organometallic reagents …..........61 2.1: Reaction with Grignard reagents. …………………..………….……….......………61 2.2: Reaction with organolithium reagents. …………………………….……..…..…….65 2.3: Studies of the role of radical pathways ………………………………..………........68 2.4: Brief summary on mechanism- two electron vs. radical. …..…..................…….….73 Section-3: Results and discussion. ……………………………………….……..……….74 3.1: Synthesis of peroxide electrophiles. ………………….……………………...……..74 3.2: Comparison of C-O bond formation using different peroxide electrophiles. ………78 3.3: Reaction of THP monoperoxyacetals with sp3 RLi and RMgX. …….……..….…...82 3.4: Application to couplings with sp2 RLi and RMgX …………………………..……..84 3.5: Application to couplings with sp RLi and RMgX …….……………………..……..85 Section-4: Preliminary computational studies of the reactions of peroxides with RLi….86 Section-5: Leaving group effects ………………………………………………...……...88 Section-6: Conclusions ……………………...……………………………….………….90 Section-7: Experimental Section. …………………...……………………….…………..91 v Section-8: References. ………………………………………………………….……...121 Chapter-4: Application of peroxides to synthesis of functionalized ethers. Section-1: Reaction of peroxides with dithianes and synthesis of S,S,O-orthoesters .....126 1.1. Previous approaches to S,S,O-Orthoesters. ……………………………..….….…..128 1.2. Reaction of peroxides with dithianes. ………………..…………….…….….…….129 Section-2: Synthesis of difluoroethers. ………………………..………..…….…….….134 2.1. Background on fluorodesulfurization. …………………..…………..……..……...134 2.2. Synthesis of difluoroethers from pure S,S,O-orthoesters. …..………..…..……….136 Section-3: Studies towards synthesis of trifluoromethyl ethers. ….…………...………137 3.1. Previous approaches for synthesis of trifluoromethyl ethers. ……………..………137 3.2. Peroxide electrophiles for trifluoromethylation. ………………………….….……141 3.3. Attempted nucleophilic trifluoromethylation of peroxides. ………….….…….…..142 3.4: Synthesis of a S,S,S,O-orthocarbonate and derived trifluoroether. ……….……….144 Section 4: Investigation of silylated cyanohydrins as nucleophiles. …………..….……148 Section-5: Synthesis of cyclopropyl ethers. ………………………………….….……..150 Section-6: Application of peroxides to synthesis of mixed acetals. ………….….…….152 6.1. Background on α-alkoxy stannanes. ……………………………………….……...152 6.2. Reaction of α-alkoxylithium reagents with peroxides. …………………….…...…154 6.3: Investigations into synthesis of 1,3-dioxetanes. …...……………………….……..156 Section-7: Experimental section. ……………………………………………….……...159 Section-9: References. …………………………...……………………………….……172 1 Chapter-1. Reductive amination of hydroperoxy acetals; application of reductive amination in tandem with ozonolysis. Portions of this chapter were reproduced from Synthesis, 2011, 3475 with the permission of the publisher.1 In this chapter, I will discuss the development of new methodology for one-pot conversion of alkenes to amines. The discussion will begin with the formation of hydroperoxy acetals from alkene ozonolysis and then discuss our development of a mild reduction of hydroperoxy acetals to carbonyl compounds using Na(OAc)3BH. The chapter will conclude with the application of this methodology to reductive amination, including a one-pot synthesis of amines from alkenes (Scheme-1). Scheme-1: O Na(OAc)3BH OOH R O3, DCM, MeOH Na(OAc)3BH R-NH R 2 R N R OMe R H H (i) O3,
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