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University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St. John's Road. Tyler's Green High Wycombe, Bucks, England HP10 8HR I I 78-5830 DETTY, Michael Ray, 1951- CON JUGAT I VE AND HOMOCONJUGATIVE INTERACTIONS OF CYCLOPROPANE RINGS IN NEUTRAL AND CATIONIC SYSTEMS. The Ohio State University, Ph.D., 1977 Chemistry, organic University Microfilms International, Ann Arbor, Michigan 48106 CONJUGATIVE AND HOMOCONJUGATIVE INTERACTIONS OF CYCLOPROPANE RINGS IN NEUTRAL AND CATIONIC SYSTEMS DISSERTATION Presented in Partial Fulfillment of the Reauirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Michael Ray Detty, B. Sc. * * * * * The Ohio State University 1977 Reading Committee: Approved by Prof. Leo A. Paguette Prof. John S. Swenton Prof. Gary G. Christoph ACKNOWLEDGEMENTS It has been an honor to have Professor Leo A. Paquette as an adviser. His enthusiasm and knowledge of chemistry have been inspirational. His guidance has been active when needed, but more subdued when the progression of research has not required it. Importantly, his day to day interest in my research was unceasing and was greatly appreciated. VITA January 23, 1951 .......... ......Born - Springfield, Ohio 1972 ............................ B. Sc., Bowling Green State University, Bowling Green, Ohio 1972-1973 ....................... Chemist, General Latex and Chemical Corporation, Ashland, Ohio 1973-1974 ....................... University Graduate Fellow, The Ohio State University, Columbus, Ohio 1974-1976 ....................... Research Assistant, The Ohio State University, Columbus, Ohio 1976-1977 ....................... University Dissertation Fellow, The Ohio State University, Columbus, Ohio PUBLICATIONS Michael R. Detty and Leo A. Paquette,"Stereocontrolled Synthesis, Con­ formational Features, and Response to Thermal Activation of the Seven Possible Bis- and Trishomocycloheptatrienes," J. Am. Chem. Soc., 99, 821 (1977). Leo A. Paquette and Michael R. Detty, ” Stereoisomeric Bishomo-3,5- cycloheptadienyl £-Toluenesulfonates as Probes of the Geometric and Conformational Dependence of Long-Range Cyclopropyl Interaction during Acetolysis," J. Am. Chem. Soc., 99, 828 (1977). iii Michael R. Detty and Leo A- Paquette, "The Fate of Bishomocyclohepta- dienyl Cations Generated by Deamination," J. Am. Chem. Soc., 99, 834 (1977). Michael R. Detty and Leo A. Paquette, "The Question of Hexahomobenzene 3 Automerization. New Synthetic Approaches to cis -1,4,7-Cyclo- nonatriene," Tetrahedron Lett., 347 (1977). FIELDS OF STUDY Major Field: Organic Chemistry iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ..................................... ii VITA ................................................. iii LIST OF TABLES ....................................... vii LIST OF FIGURES ...................................... viii Chapter I. Synthesis and Properties of the Bis­ and Trishomocycloheptatrienes..................... 1 INTRODUCTION.................................... 2 RESULTS AND DISCUSSION ......................... 9 Chapter II. The Question of Hexahomobenzene Automerization..................................... 38 INTRODUCTION.................................... 39 RESULTS AND DISCUSSION ......................... 42 Chapter III. Studies of Long-Range Cyclopropane Interactions with Carbonium Ion Centers. Con­ trasting Behavior of Cations Generated by Sol- volysis and Deamination in the 3,5-Bishomocyclo- heptadienyl System................................. 47 INTRODUCTION .................................... 48 RESULTS AND DISCUSSION .......................... 52 Chapter IV. Functionalization of the Bishomocyclo- heptatrienes. Studies of Cyclopropyl Halide Solvolysis and 1,3-Bishomotropylium Cations....... 84 v Page INTRODUCTION .................................... 85 RESULTS AND DISCUSSION .......................... 94 EXPERIMENTAL ......................................... 127 REFERENCES ........................................... 201 vi LIST OF TABLES Table 1 O Page 1 C Chemical Shift Data of the Trishomocycloheptatrienes.... 18 2 Kinetic and Thermodynamic Data for the Thermal Rearrangement of 34.......................................... 22 3 Kinetic and Thermodynamic Data for the Thermal Rearrangement of 88......................................... 26 4 Kinetic Data for Acetolysis in Buffered Acetic Acid......... 58 5 NMR Spectra of the Isomeric Bicyclo[6.1.0]non-3- en-6-yl Acetates and Their Deuterated Derivatives............ 60 6 NMR Data for the 1,3-Bishomotropylium Cation............... 112 7 NMR Data for Unprotonated and Protonated 256............... 115 8 NMR Data for Unprotonated and Protonated J251............... 116 9 Kinetic Data for Solvolysis in 80% Aqueous Acetone......... 120 vii LIST OF FIGURES Figure Page 1 1,5-Dienyl and Homo-1,5-Dienyl Hydrogen Shifts in Bicyclo[6.1.0]nonadienyl Systems....................... 23 viii Chapter I. Synthesis and Properties of the Bis- and Trishpmocycloheptatrienes. 1 INTRODUCTION Hie concepts of homoconjugation and homoaromaticity have elicited much interest in recent times. ^ Of particular interest have been cyclic polyene systems in which the conjugated rr ribbon has been interrupted one or more times by a methylene unit or by substitution of a cyclopro­ pane ring for a double bond. 1,3,5-Cycloheptatriene (1) is a represent­ ative of such a molecular type and has often been referred to as homo­ benzeneo . 2 1 2 sw (V 3 The question of whether cycloheptatriene and its derivatives are neutral homoaromatic molecules is one of long standing. A central issue has been whether or not cycloheptatriene (1) is in equilibrium with its norcaradiene valence isomer (2), or whether cycloheptatriene is best thought of as a resonance hybrid of the two as in 3. From electron diffraction and NMR studies, it is clear that cycloheptatriene adopts a boat shaped conformation as in j4 with a barrier to degenerate ring 3—5 inversion of about 6 kcal/mole. Although the existence of an H. AH* = 6 kcal/mole 4a 4b equilibrium between cycloheptatriene and norcaradiene cannot be detected experimentally, ® many of its reactions imply the existence of fL Its thermal conversion to toluene and capture by dienophiles in Diels-Alder reactions are best explained as arising from the norcaradiene tautomer. ^-13 More convincing evidence for this equilibrium comes from 7.7-disubstituted cycloheptatrienes where 5^ and 6 have been isolated as separate entities and £ has been shown to be the preferred form of the 7.7-dicyano derivative. *4-16 Direct analysis of the NMR spectrum of M £• * M *1 Q cycloheptatriene and diamagnetic susceptibility data provide evidence that cycloheptatriene can support an induced diamagnetic ring current. Finally, theoretical calculations combined with the photo- CN CN CF: CN 6 7 /w ^ electron spectrum of 1 argue for the existence of a small homoaromatic interaction between the two carbons at the termini of the triene unit. 19'20 The theoretical calculations mentioned above are based on the structural parameters of cycloheptatriene determined by electron diffraction studies. 3 The hydrocarbon adopts a boat conformation (4) with the methylene group and the opposite carbon-carbon double bond bent out of the basal plane. The intemuclear distance between and Cfc was O determined to be 2.511 A and the p orbitals on these carbons were canted toward each other at an angle of 67.42° relative to the basal plane. 3 Through the use of vector analysis and Slater orbitals, the extent of interpenetration of these p orbitals as given by the overlap integral S was found to be 0.042, which is indicative