Oxidation of organic compounds by dioxiranes

678 Pages·2009·99.24 MB·English

by  Waldemar Adam

Oxidation of Organic
Compounds by
Dioxiranes
Oxidation of Organic
Compounds by
Dioxiranes
WALDEMAR ADAM
CONG-GUI ZHAO
CHANTU R. SAHA-MO¨LLER
KAVITHA JAKKA
JOHN WILEY &SONS,INC.,PUBLICATION
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ISBN978-0-470-45407-7
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10987654321
CONTENTS
CHAPTER PAGE
FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
PREFACEAND ACKNOWLEDGMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
1. DIOXIRANE EPOXIDATIONOF ALKENES
Waldemar Adam, Chantu R. Saha-Mo¨ller, and Cong-GuiZhao . . . . 1
2. DIOXIRANE OXIDATIONSOF COMPOUNDS OTHERTHAN ALKENES
Waldemar Adam, Cong-GuiZhao, and KavithaJakka . . . . . . . . . . 311
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 663
v
FOREWORD
Chemical synthesis is an intellectually and technically challenging enterprise.
Over the many decades of progress in this discipline, spectacular advances in
methods have made once intimidating transformations now routine. However,
as the frontier advances and the demands for ready access to greater molecular
complexityincreases,sodoesthesophisticationofthechemicalreactionsneeded
to achieve these goals. With this greater sophistication (and the attendant expec-
tation of enhanced generality, efficiency, and selectivity) comes the challenge
of adapting these technologies to the specific applications needed by the prac-
titioner. In its 66-year history, Organic Reactions has endeavored to meet this
challenge by providing focused, scholarly, and comprehensive overviews of a
given transformation.
By any yardstick, the oxidation of organic compounds is one of the most
important methods for the introduction and manipulation of functional groups.
No fewer than 24 of the 239 chapters in the Organic Reactions series are ded-
icated to oxidation in one if its manifold forms. Among the most modern of
these transformations is the use of the fascinating family of oxidants known as
dioxiranes. Although humble in size, dioxiranes can effect a remarkable array
of oxidative processes by transferring one oxygen atom to organic substrates. In
addition,totheirvirtuosity,dioxiranescanbegeneratedcatalyticallyandproduce
no toxic waste stream as part of the oxidation process. Moreover, some of the
most exciting recent developments involve the enantioselective introduction of
oxygen atoms via chiral dioxiranes.
The Organic Reactions series is fortunate to have published two chapters on
dioxiraneoxidations,oneinVolume61onalkeneoxidationandoneinVolume69
onoxidationofallotherorganicsubstrates.Bothofthesecomprehensivechapters
wereauthoredby one of the internationally recognizedleadersin this field,Prof.
Waldemar Adam and his coworkers. Although many reviews and book chapters
have been written on dioxirane oxidations, remarkably, there is no single book
dedicatedto this important topic. Thus, in keeping with our educational mission,
the Board of Editors of Organic Reactions has decided to combine these two
chapters to create the definitive resource for dioxirane oxidations. In addition, to
keep pace with the rapid development of this field, Professors Adam and Zhao
have compiled updated lists of references for each of the chapters that bring the
literature coverage up to June 2008. These lists are appended at the end of each
chapter and are organized by the Tabular presentation of the different classes of
oxidation.
vii
viii FOREWORD
The publication of this book represents the third soft cover reproduction of
OrganicReactions chapters. The success of the first two soft cover books (“The
Stille Reaction” taken from Volume 50 and “Handbook of Nucleoside Synthe-
sis” taken from Volume 55) has convinced us that the availability of low-cost,
high-quality publications that cover broadly useful transformations is addressing
an unmet need in the litarature of organic synthesis. Thus we will continue to
identify appropriate candidates for the compilation of such individual volumes
as opportunities present themselves.
Scott E. Denmark
Urbana, Illinois
PREFACE AND ACKNOWLEDGMENTS
Although the dioxirane structure was proposed as an intermediate in the Baeyer-
Villigeroxidationalreadyin1899,thechemistryofdioxiranesdidnotcommence
until 1974, when Montgomery observed the ketone-catalyzed decomposition of
®
potassium monoperoxysulfate (Oxone ). Shortly after this pivotal discovery,
Edwards inferred that the plausible intermediate in this reaction should be the
dioxirane molecule. A microwave structure determination confirmed the unusual
three-membered-ringperoxide.Inthenextthirty-fiveyears,theworldwidechem-
ical community witnessed an exponential development of dioxirane chemistry.
So far well over one thousand research articles have appeared that discuss
the structure, properties, reactivity, selectivity, theoretical aspects, and synthetic
applications of these highly reactive, yet mild oxidants. Through these efforts,
dioxiranes,especiallydimethyldioxirane(DMD),havebecomeindispensableoxi-
dants for the synthetic organic chemist.
Thehighpopularityofthesenovelcompoundsisduetothefactthatdioxiranes
constitute an ideal oxidant in many respects. These reagents perform a variety
of versatile oxidations, exhibit unusual reactivity, and conduct the oxygen trans-
fer highly chemo-, regio-, and stereoselectively. They are readily prepared from
®
a suitable ketone, such as acetone, and Oxone , which are cheap yet environ-
mentally benign bulk chemicals. Furthermore, since the dioxirane is reduced
to the ketone precursor during the oxygen transfer, the oxidation may be run
catalytically.
Dioxirane oxidations are carried out either with the isolated dioxirane (as a
solution) or with the in-situ-generated dioxirane from a suitable ketone precur-
sor. The advantage of using isolated dioxirane solutions is that the oxidations
can be performed under strictly neutral and anhydrous conditions, which allows
the isolation of some very elusive and sensitive oxidation products. This method
is limited because the oxidation has to be carried out on a small scale due to the
low dioxirane concentration in the isolated solution. Such problems are readily
circumvented by the use of in-situ-generated dioxiranes, which may be scaled
up. Although the in-situ mode cannot be applied to substrates and products that
are sensitive to water, the oxidation canbe conducted catalytically. The catalytic
mode of operation has become important for the dioxirane-mediated asymmetric
oxidations,sincetheketoneprecursorsaregenerallynotreadilyavailable.Dioxi-
ranes can be employed to oxidize heteroatoms, epoxidize π bonds, and insert
into C-H and Si-H bonds. The difficulty of the oxidation increases in that order
for these electrophilic oxidants.
ix
x PREFACEANDACKNOWLEDGMENTS
The book contains two chapters that cover the diverse oxidations that have
been reported. The first chapter comprises the dioxirane oxidations of alkenes,
the most studied oxygen-transfer reaction. The second chapter covers all of the
remainingtypesofdioxirane oxidations, namelyheteroatomsubstrates, saturated
groupings, and organometallic compounds. For each specific type of oxidation,
the presentation begins with a brief discussion of the reaction mechanism, fol-
lowedbythescopeandlimitationsoftheoxidationunderconsideration,together
with a brief comparison with other reported oxidation methods. Our incentive is
to give the reader a general idea of the usefulness of these oxidants in sufficient
detail so that an intelligent choice may be made, especially by those who use
this oxidant for the first time. In the case of the epoxidations, since the reactiv-
ity of the alkene substrates and the selectivities of the oxygen-transfer process
are critical in making a proper choice, we cover the scope and limitations indi-
vidually. Similarly, the scope and limitations of the oxidations of alkynes and
arenes, diverse heteroatoms, alkanes and silanes, and organometallic compounds
are discussed separately in view of the different nature and/or outcome of these
oxygen-transfer processes.
Inthesectionsonexperimentalconditions,somegeneralguidelinesonhowto
select the reaction parameters are given. Some representative experimental pro-
ceduresarethenprovidedthatshouldbehelpfulincarryingouttheseoxidations.
Whereas for a given oxidation the reaction conditions may still need to be opti-
mized,theseproceduresshouldhelpthereaderstounderstandthemostimportant
features of these experiments. Finally a tabular survey of the reported dioxirane-
mediatedoxidationsiscollected.Chapter1containsninetables,whereasChapter
2 comprises as many as 21 tables. Most of these tables are organized according
to reaction types. For the same type of oxidation, if the substrate, selectivity,
or the reaction conditions are of crucial importance to the oxidation, then these
cases are presented in separate tables. Reaction conditions, such as temperature,
reaction time, solvent, are specified explicitly. The product structures and their
yields, as well as the diastereomeric ratios and enantiomeric excess values, if
available, are presented in these tables. In each of these tables, the reactions
are arranged in ascending order of carbon atoms of the substrates to facilitate
browsing.
Since dioxirane chemistry has expanded quickly in recent years, an update
of the most recent publications is also provided on the work that has appeared
afterthesetwochapterswerepublished.Particularemphasisisplacedonsynthetic
applicationsandasymmetricepoxidationstoapprisethereaderofthemostrecent
advances. These literature references have been collected in separate sections
according to the sequence of the tables in the Tabular Survey section of these
two chapters.Ineachof the sections, the individual citations have beenarranged
in alphabetic order of the author names.
Althoughthereareseveralexcellentandextensivereviewarticlesavailableon
dioxiraneoxidations,mostoftheseareofaspecificratherthangeneralcharacter.
The purpose of this book is to summarize all the past achievements in the field
andprovidethereaderwithadetailedaccountoftheexperimentalprocedures.We
PREFACEANDACKNOWLEDGMENTS xi
believe that the elaborate tabular compilations should be of help to all organic
chemists engaged in oxidation chemistry, whether of mechanistic or synthetic
interest.
ACKNOWLEDGMENTS
Generous financial support of the Deutsche Forschungsgemeinschaft (Schwer-
punktprogramm “Peroxidchemie: Mechanistische und Pra¨parative Aspekte des
Sauerstofftransfers” and Sonderforschungsbereich SFB 347 “Selektive Reaktio-
nenMetall-aktivierterMoleku¨le”),theFondsderChemischenIndustrie,theNIH-
MBRSSCOREProgram(GrantNo.S06GM08194;1SC1GM082718-01A1),the
Welch Foundation (Grant No. AX-1593) and the DAAD (Deutscher Akademis-
cherAustauschdienst) are gratefully appreciated. We also thank Mrs. Ana-Maria
Krause for her help in preparing the tabular and graphical material.
C.-G. Zhao
San Antonio, TX USA
W. Adam
Rio Piedras, PR USA
CHAPTER 1
DIOXIRANE EPOXIDATION OF ALKENES
WALDEMAR ADAM, CHANTU R. SAHA-MO¨LLER,AND CONG-GUI ZHAO
Institut fu¨r Organische Chemie,Universita¨t Wu¨rzburg,
D-97074 Wu¨rzburg, Germany
CONTENTS
PAGE
ACKNOWLEDGMENTS . . . . . . . . . . . . . 2
INTRODUCTION . . . . . . . . . . . . . . 3
MECHANISM . . . . . . . . . . . . . . 4
SCOPEANDLIMITATIONS . . . . . . . . . . . . 6
EpoxidationofUnfunctionalizedAlkenes . . . . . . . . 6
EpoxidationofElectron-RichAlkenes . . . . . . . . . 8
EpoxidationofElectron-PoorAlkenes . . . . . . . . . 10
EpoxidationofAlkeneswithbothElectronDonorsandElectronAcceptors . . 11
Chemoselectivity . . . . . . . . . . . . . 12
Regioselectivity . . . . . . . . . . . . . 18
Diastereoselectivity . . . . . . . . . . . . 20
Enantioselectivity . . . . . . . . . . . . . 23
COMPARISONWITHOTHERMETHODS . . . . . . . . . . 29
EXPERIMENTALCONDITIONS . . . . . . . . . . . 31
OxidationswithIsolatedDioxiranes . . . . . . . . . 31
General . . . . . . . . . . . . . . 31
Solvents . . . . . . . . . . . . . . 33
Temperature . . . . . . . . . . . . . 33
OxidationswithinsituGeneratedDioxiranes . . . . . . . 33
OxidationsunderNeutralConditions . . . . . . . . . 33
BiphasicMedia . . . . . . . . . . . . . 33
HomogeneousMedia . . . . . . . . . . . . 34
OxidationsunderBasicConditionsinHomogeneousMedia . . . . . 34
EXPERIMENTALPROCEDURES . . . . . . . . . . . 34
PreparationofIsolatedDioxiraneSolutions . . . . . . . . 34
Dimethyldioxirane[DMD(isol.)] . . . . . . . . . 34
Dimethyldioxirane-d inAcetone-d [DMD-d (isol.)] . . . . . 35
6 6 6
DimethyldioxiraneinCarbonTetrachloride . . . . . . . 35
OxidationofOrganicCompoundsbyDioxiranes,byWaldemarAdam,Cong-GuiZhao,ChantuR.
Saha-Mo¨ller,andKavithaJakka
©2009OrganicReactions,Inc.PublishedbyJohnWiley&Sons,Inc.
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