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The Carbonylation Reaction of Organoboranes in the Presence of Lithium Triethylborohydride

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The Carbonylation Reaction of Organoboranes in the Presence of Lithium Triethylborohydride W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 1975 The Carbonylation Reaction of Organoboranes in the Presence of Lithium Triethylborohydride Robert Cloyd Shiffer College of William & Mary - Arts & Sciences Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Organic Chemistry Commons Recommended Citation Shiffer, Robert Cloyd, "The Carbonylation Reaction of Organoboranes in the Presence of Lithium Triethylborohydride" (1975). Dissertations, Theses, and Masters Projects. Paper 1539624896. https://dx.doi.org/doi:10.21220/s2-z8kr-ve76 This Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. THE CARBONYLATION REACTION OF ORGANOBORANES U IN THE PRESENCE OF LITHIUM TRIETHYLBOROHYDRIDE A Thesis Presented to The Faculty of the Department of Chemistry The College of William and Mary in Virginia In Partial Fulfillment Of the Requirements for the Degree of Master of Arts by Robert C. Shiffer, Jr. 1975 To my family 61553 9 APPROVAL SHEET This thesis is submitted in partial fulfillment of the requirements for the degree of Master of Arts Robert C. Shaffer Approved, January 1975 Randolph A. Coleman, Ph.D. Robert A. Orwoll, Ph.D. Melvyn D. £> chi ave 1 li, Ph. D. iii TABLE OF CONTENTS ACKNOWLEDGMENT ................................. vi LIST OF TABLES ............ vii LIST OF FIGURES . ............ viii ABSTRACT ................................. ix Chapter I. INTRODUCTION................................... 2 II. THE CARBONYLATION OF B-ALKYL-9-BBN DERIVATIVES IN THE PRESENCE OF' LITHIUM TRIETHYLBOROHYDRIDE OXIDATION OF THE REACTION INTERMEDIATES TO THE CORRESPONDING ALDEHYDES ; ................................... 12 Introduction.................................. 12 Results ......... .................. 13 Discussion................................... 27 Experimental . ................. 32 III. THE CARBONYLATION OF B-ALKYL-9-BBN INTERMEDIATES IN THE PRESENCE OF LITHIUM TRIETHYLBOROHYDRIDE, ATTEMPTED ISOLATION OF HOMOLOGATED ALDEHYDES ........................ 43 Introduction.. ................................ 43 R e s u l t s ......................................' 45 Discussion . .............................. 49 Experimental ................................ 52 iv V Chapter IV. THE CARBONYLATION OF B-ALKYL-9-BBN DERIVATIVES IN THE PRESENCE OF LITHIUM TRIETHYLBORODEUTERIDE. OXIDATION TO THE HOMOLOGATED D^-ALDEHYDES ..................... 58 Introduction ............................... 58 Results ....... .... 64 Discussion ........ 71 Experimental.......... 72 V. COMPARISON OF THE CARBONYLATION OF B-ALKYL- 9-BBN DERIVATIVES IN THE PRESENCE OF VARIOUS METAL HYDRIDES. A STUDY IN STERIC CONTROL ..................................... 76 Introduction ................ 76 R e s u l t s ................................... 81 Discussion................................. 82 Experimental ......... ........ 86 VI. POSSIBLE EXTENSIONS OF THE CARBONYLATION OF B-ALKYL-9-BBN DERIVATIVES IN THE PRESENCE OF LITHIUM TRIETHYLBOROHYDRIDE- . 89 Introduction ............... 89 Results . 91 Discussion.............. 94 Experimental ..... .......... ..... 95 ACKNOWLEDGMENTS The writer wishes to express his sincere appreciation to Professor Randolph A. Coleman, under whose guidance this investi­ gation was conducted, for his patient guidance and understanding throughout the course of this investigation. The author is also indebted to Professor Robert A. Orwoll and Professor Melvyn D. Schiavelli for their careful reading and criticism of this manuscript. vi 0 LIST OF TABLES Table Page I. Carbonylation of Various B-Alkyl-9-BBN Intermediates in the Presence of Lithium Triethylborohydride Oxidation in Hydrogen Peroxide, pH 9.5 Phosphate Salt Solutions at 2 5 ° .......................... 16 II. The Oxidation of TrialkyIboranes in the Presence of 30 Percent Hydrogen Peroxide. Conditions S t u d y ........................... 17 III. Carbonylation of Various B-Alky1-9-BBN Intermediates in the Presence of Lithium Triethylborohydride. Oxidation in Hydrogen Peroxide, pH 9.5 Phosphate Salt Solutions. ........ 19 IV. The Carbonylation of Various B-Alkyl-9-BBN Intermediates in the Presence of Lithium Triethylborohydride at Different Temperatures ....................................... 21 V. The Carbonylation of B-hexyl-9-BBN in the Presence of Various Ratios of Lithium Triethylborohydride . ........................... 22 VI. Preparation of d'^-Aldehydes via the Carbonylation of B-Alkyl-9-BBN Derivatives in the Presence of Lithium Triethylborohydride .......... 65 VII. Comparative Reaction Yields for the Reactions of B-Alky1-9-BBN Intermediates in the Presence of LiEt^BH, LiAl(0-t-Bu)3H, and LiAl(OCH3)3H ......... .4........................... 83 vii LIST OF FIGURES Figure Page I. Infrared Spectrum of Heptaldehyde ..................... 23 II. Nmr Spectrum of H e p t a l d e h y d e ............ 24 III. Infrared Spectrum of Cyclohexanecarboxaldehyde.... 25 IV. Nmr Spectrum of Cyclohexanecarboxaldehyde ............ 26 V. Brown C a r b o n y l a t o r .............. 36 VI. Nmr Spectrum of Cyclohexanecarboxylic A c i d ...... 55 VII. Infrared Spectrum of d^-Heptaldehyde............... 66 VIII. Nmr Spectrum of d^-Heptaldehyde................ 67 IX. Infrared Spectrum of d^-Cyclohexanecarboxaldehyde . 68 X. Nmr Spectrum of d^Cyclohexanecarboxaldehyde... 69 XI. Nmr Spectrum of d^-ll-Carbomethoxyundecanal........ .. 70 XII. Infrared Spectrum of 11-Carbomethoxyundecanal ......... 92 XIII. Nmr Spectrum of 11-Carbomethoxyundecanal ....... 93 viii ABSTRACT The reaction of B-alkyl-9-Borabicyclo [3.3.l]nonane derivatives with carbon monoxide in the presence of lithium tri­ ethylborohydride has been shown to produce an intermediate which can readily be oxidized to the homologated aldehyde. With this reaction, primary, internal and cyclic olefins can be converted into the homologated aldehyde in good yield. Thus, cyclohexene is con­ verted into cyclohexane carboxaldehyde in 75 percent yield. Preliminary studies indicate that functionally substituted olefins can be accommodated. Thus, methyl-10-undecenoate is converted into 11-carbomethoxyundecanal in 61-percent yield. By utilizing lithium triethylborodeuteride, d^-aldehydes can be produced in like yields. Nmr and I.R. studies show deuterium incorporation of 98 percent to 100 percent in the formed d^-aldehydes. ix THE CARBONYLATION REACTION OF ORGANOBORANES IN THE PRESENCE OF LITHIUM TRIETHYLBOROHYDRIDE CHAPTER I INTRODUCTION The general hydroboration reaction of olefins, discovered in 1956,^ is probably the single most important contributor to the use of organoboranes as synthetic intermediates. In this reaction, Borane, a mild reducing agent comparable to NaBH^, was shown to add in a cis-fashion to the least hindered side of a double bond, BD3 + \ J \\ TOF > \ / \~ " 90% thus, allowing the cheap, easy synthesis of organoboranes. Without it, the possible use of carbonylated organoboranes as synthetic intermediates may never have been explored. Early explorations of the. reaction of carbon monoxide with 2 boron-containing compounds were headed by Burg and Schlesinger. In 1936, they achieved the addition of carbon monoxide to diborane. The reaction occurred in a sealed tube at 100° under 20 atmospheres of carbon monoxide pressure and yielded the addition compound borane carbonyl. 1/2(BH) + C0f=* H3BC0 Borane carbonyl boils at -64° and is largely dissociated into its 2 components at atmospheric pressure. At the same time, the addition 3 of carbon monoxide to the methyl derivatives of diborane was found to occur at five atmospheres CO pressure to give a number of rather complex materials. The major one, with empirical formula j(CH^^BHCOf2> did not liberate hydrogen when treated with water. The compound thus had no easy hydrolyzable boron-hydrogen bonds and, 4 in light of recent studies, probably was: CH CH CH CH Significantly, no carbon monoxide uptake was reported for the attempted reaction, under the same conditions, of CO with trimethyl- borane* It remained until 1961, and the advent of a*wider variety of more easily synthesized organoboranes, that the further studies by W. Reppe and A. Magin^ resulted in the issuance of a patent for the carbonylation of trialkylboranes under pressure. The resulting (R^BCO)^ compounds were formed by the reaction of a trialkylborane with carbon monoxide at pressures of 100 to 200 atmospheres and temperatures of 10 to 20 degrees. After reaction mixture distillation, the major product was found to be (R^BCO)^ and the minor one (R^BCO)^. 4 g Mellville Hillman, at Dupont, in 1962 and 1963 first described the structures of these products. By running the same reaction at pressures of 500-1000 atmospheres, he achieved the formation of 2,5-diboradioxanes (I) at 50° C. Upon hydrolysis of the B-C bonds with alkaline hydrogen peroxide, the corresponding dialkyl carbinols were produced. I -> 2R0H + 2R0 COH 2 2 2 If the reaction was run at higher temperatures, generally 150°, the corresponding boronic anhydrides (boroxines) were formed. .CR 150 500-1000 atm Thus, in order to explain these results, Hillman postulated the following mechanism: This takes into account the facts that boron is: 1. a good Lewis acid, having a low lying (energywise) empty p-orbital for carbon monoxide to attack, and
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