Stereoselective synthesis. 3, Stereoselective pericyclic reactions, cross coupling, C-H and C-X activation

1056 Pages·2011·11.52 MB·English

by  Evans

VII
Volume Editors(cid:2) Preface
Remarkableadvancementsinstereoselectivesynthesishaveoccurredoverthepasthalf-
century. For decades, the Diels–Alder reaction was perhaps the only reaction providing
reliably high and predictable stereoselectivity with broadly applicable efficacy. Subse-
quentdevelopmentsincatalyticasymmetrichydrogenationsandoxidationsofalkenes,
asymmetric hydroborations, and diastereoselective/enantioselective aldol reactions,
amongothers,openedthefloodgatestoahostofhighlytunedreactionsthatprovidedac-
cesstocompoundsinstunninglyhighdiastereo-andenantioselectivities.Thisevolution
was alluded to in the preface to Houben–Weyl, Vol. E 21 (Stereoselective Synthesis,
published in 1995), wherein Helmchen, Hoffmann, Mulzer, and Schaumann pointed to
theenormousprogressinstereoselectivitymadeinthe20yearspriortotheirextraordi-
narycontribution.
Intheintervening15years,onecanseethatfurtheradvancementshavebeen,ifany-
thing,evenmorebreathtakinglyimpressive.Whereasinthe1970sa4:1stereoselectivity
inanygivenreactionmighthavebeenacceptable,ifnotremarkable,andinthe1990sthe
goal of 20:1 stereoselectivity was achieved in pockets of transformations of variable
scope,in2010anythinglessthan20:1stereoselectivityacrossawiderangeoftransforma-
tionsandreactingpartnersisnowdecidedlyunacceptable.
Thesemanyadvancementscalledforanupdatethatwastimely,state-of-the-art,and
focusedonthosemodernmethodslikelytoinfluencethecourseoforganicsynthesisfor
theforeseeablefuture.TheresultisStereoselectiveSynthesis,apartoftheScienceof
SynthesisReferenceLibrary.StereoselectiveSynthesisisamajorreferenceworkthat
criticallyreviewsthestatusofthedisciplineandservesasafoundationtoforgethefuture
ofthefield.AlthoughtheoriginalStereoselectiveSynthesisfocusedlargelyonstoichio-
metric methods, the increasing significance of catalytic processes has transformed the
field. This latest version of Stereoselective Synthesis reflects and highlights the stun-
ningadvancementsinthesemanycatalyticmethods(metal-based,organocatalytic,oren-
zymatic), in addition to reemphasizing the importance of stoichiometric transforma-
tions.
Unlikeotherreferenceworks,StereoselectiveSynthesisisnotacomprehensivere-
viewortreatise,butratheracriticalselectionofthosesyntheticmethodsthatareviewed
bydistinguishedexpertsasmostsignificant.Typicalorgeneralexperimentalprocedures
for the methods have been carefully selected. In evaluating protocols for inclusion, the
authorswereaskedtoconsideryields,selectivities,breadthofapplicability,atomecono-
my, robustness, scalability, and environmental impact. The result is a snapshot of the
best,mostusefulsyntheticmethodsavailableforconstructingawiderangeofimportant
organicsubstructures.
TheorganizationofStereoselectiveSynthesisisbasedonsyntheticmethods,which
arearrangedaccordingtothetypeofreaction.Thecontributionshavebeendividedinto
three volumes. Volume 1 considers stereoselective reactions of carbon-carbon double
bonds. In the second volume, stereoselective reactions of carbonyl and imine groups
havebeencollected.Thethirdvolumediscussespericyclicreactions,cross-couplingreac-
tions,and reactions taking place byC–Hand C–Xactivation. Each chapter withinthese
volumescoversaspecificsyntheticmethod.
Science of Synthesis Reference Library
Stereoselective Synthesis
© Georg Thieme Verlag KG
VIII VolumeEditors(cid:2)Preface
TheEditorshavebenefitedtremendouslyfromtheexpertiseanddedicatedeffortsof
alloftheauthorswhohavedevotedtheirvaluabletimeandenergytoparticipateinthis
unique contribution. We thank all of these individuals, as well as the editorial staff in
Stuttgart,fortheoutstandingeffortstheyhavemadethroughouttheentirepublication
process,makingStereoselectiveSynthesisagoldstandardinThieme(cid:5)sScienceofSyn-
thesisreferenceseries.
VolumeEditors October2010
J.G.deVries(Geleen,theNetherlands)
P.A.Evans(Liverpool,UK)
G.A.Molander(Philadelphia,USA)
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XI
Abstracts
p7
3.1 [m+n]-CycloadditionReactions(Excluding[4+2])
G.-J.Jiang,Y.Wang,andZ.-X.Yu
Thismanuscriptcoversasymmetric[m+n]cycloadditionsforthesynthesisoffour-tosev-
en-memberedringsandnine-memberedrings,catalyzedbytransitionmetalsororganic
moleculesusingeitherchiralligandsorchiralcatalystsasthechiralsources.Thesecyclo-
additionreactionscanconstructmono-,bi-,orevenpolycycliccompoundsandgenerate
uptofourstereocentersinonepot,providinghighefficiencyinsynthesis.
X1m
chiral catalyst
X1m + X2n
m + n = 4−7, 9 X2n
Keywords: asymmetriccycloaddition•[m+n]cycloaddition•C-Cbondformation•chi-
ralcatalysts•chiralligands•four-memberedrings•five-memberedrings•six-membered
rings•seven-memberedrings•nine-memberedrings
p67
3.2 [4+2]-CycloadditionReactions
K.IshiharaandA.Sakakura
The Diels–Alderreaction is one of themost powerful organictransformations available
andisaversatiletoolforthesynthesisofmanybioactivenaturalproducts.Sincethedis-
coveryoftheeffectivepromotionoftheDiels–AlderreactionbyLewisacids,stereoselec-
tive versions have been extensively investigated. The presence of Lewis acid catalysts
bearingchiralligandsallowstheDiels–Alderreactiontobeconductedundermildcondi-
tions,andregio-,diastereo-,andenantioselectivereactionscanbeachieved.Inaddition,
organocatalysis has been successfully applied to the asymmetric Diels–Alder reaction.
Various chiral catalysts for the asymmetric hetero-Diels–Alder reactions are also de-
scribedinthismanuscript.
O O
∗
ML (cat.) ∗
R1 + R2 X R1 R2 X
M = B, Cu, H, etc.
Keywords: asymmetriccatalysis•Brønstedacidcatalysts•cycloaddition•diastereoselec-
tivity•Diels–Alderreaction•dienes•dienophiles•enantioselectivity•hetero-Diels–Alder
reaction•Lewisacidcatalysts
p125
3.3 [m+n+1]-CarbocyclizationReactions
T.Shibata
Inthischapter[2+2+1]-carbocyclizationreactionsarediscussedandtheenantioselective
Pauson–Khand reaction, namely a carbonylative alkyne–alkene coupling, is described
comprehensively. Reactions catalyzed by chiral titanium, rhodium, iridium, and cobalt
complexesareincluded.Theuseofaldehydesasacarbonmonoxidedonorinplaceoftox-
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XII Abstracts
ic carbon monoxide gas is also discussed. Other stereoselective and/or regioselective
[m+n+1]carbocyclizations,suchas[3+2+1],[4+2+1],and[5+2+1]reactions,arealsode-
scribed.
R1
R1 chiral Co, Ir, Rh, or Ti catalyst
X R2 CO(g) or R3CHO
X ∗ O
R2
Keywords: aldehydes•alkyne–alkenecoupling•bicyclopentenones•carbonylation•
carbocyclization•cobaltcatalysis•enynes•iridiumcatalysis•Pauson–Khandreaction•
titaniumcatalysis•rhodiumcatalysis
p145
3.4 [m+n+2]-CarbocyclizationReactions
C.Aubert,M.Malacria,andC.Ollivier
The [m+n+2] carbocyclization reactions of unsaturated compounds, which include the
[2+2+2], [3+2+2], and [4+2+2] cyclizations, provide a very powerful synthetic tool for
the construction of several carbon-carbon bonds in a single chemical transformation.
The selection of the transition-metal catalyst, which orchestrates the cyclization reac-
tions, is critical for attaining optimal chemo-, regio-, and stereoselectivity. This review
outlinesthevariousfactorsthatgoverntheseimportantprocessesusingnumerousexam-
plestoillustratethesyntheticutility.
[2 + 2 + 2]
MeO OMe
, [Rh]∗ OMe
TsN
OMe
R1 = H; R2 = Me 81%; 97% ee
TsN
R1 R2 [4 + 2 + 2]
, [Rh]
TsN
R1 = Me; R2 = H 75%
H
[3 + 2 + 2]
O H
, [Rh] O
TsN TsN
91%
Keywords: asymmetriccatalysis•asymmetricsynthesis•chirality•cocyclization•cyclic
compounds•[2+2+2]cycloaddition•[3+2+2]cycloaddition•[4+2+2]cycloaddition•cy-
clotrimerization•diastereoselectivity•enantioselectivity•greenchemistry•homoge-
neouscatalysis•transitionmetals
p243
3.5 AsymmetricCycloisomerizations
I.D.G.WatsonandF.D.Toste
Thischapterwilldescribetopicsrelatingtotheasymmetriccycloisomerizationreaction.
Itwillsummarizesomeofthemostimportantandrecentdevelopmentsinthisarea.The
chapter will focus primarily on asymmetric C-C bond-forming cycloisomerizations, al-
thoughsomeC-Xbond-formingreactions(whereX=heteroatom)aredescribed.Inpar-
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Abstracts XIII
ticular, ene–yne and diene cycloisomerization, carbonyl-ene, Conia-ene, intramolecular
hydroacylationandhydrosilationreactionswillbediscussed.
O
O
5 mol% {Rh[(S)-BINAP]}SbF6
1,2-dichloroethane, rt, 12 h
86%; >99% ee
HO
CHO
OH
O
O
HO2C N
H
OH
O
(−)-platensimycin
Keywords: Alder–enereactions•asymmetriccycloisomerization•asymmetriccatalysis•
atomeconomy•carbocycliccompounds•carbonyl-enereactions•C-Hactivation•Conia-
enereactions•cyclization•hydroacylation•hydrosilylation•intramolecularreactions
p309
3.6 EneReactions
M.Terada
Thismanuscriptfocusesonrecentachievementsinthedevelopmentofasymmetricene
reactions using chiral metal catalysts and organocatalysts. The contents are divided be-
tween intra- and intermolecular reactions, and are further subdivided according to the
specific type of enophile used, including aldehydes, ketones, imines, alkynes, alkenes,
andheteroatom-containingdoublebonds.
enophile: R1Y...X cohriral metal complex R1Y...X
organocatalyst
R2 ∗ H
ene: R2 H
Keywords: acidcatalysts•asymmetriccatalysts•C-Cbonds•carbonyladditions•chiral
compounds•enantioselectivity•enereactions•homoallylicalcohols•intramolecularre-
actions•Lewisacidcatalysts•organocatalysts•pericyclicreactions
p347
3.7 SigmatropicRearrangements
J.ZehandM.Hiersemann
This manuscript covers stereoselective sigmatropic rearrangements, i.e. the Claisen,
Cope,and[2,3]-Wittigrearrangement.Itfocusesonexamplesfromnaturalproductsyn-
thesesbetween2005and2009.
X X
O
O
X = O Claisen rearrangement [2,3]-Wittig rearrangement
X = C Cope rearrangement
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XIV Abstracts
Keywords: asymmetricsynthesis•sigmatropicrearrangements•Claisenrearrange-
ment•Ireland–Claisenrearrangement•Coperearrangement•[2,3]-Wittigrearrange-
ment•carbonylcompounds•C-Cbonds•homoallylicalcohols
p383
3.8 ElectrocyclicReactions
B.GasparandD.Trauner
Electrocyclic reactions have provided many classic examples of stereoselectivity gov-
ernedbyorbitalsymmetry.Herein,wediscusstheuseinsynthesisofelectrocyclizations
andelectrocyclicringopeningsinvolvingfour,six,andeight(cid:2)-electrons.Bothall-carbon
systemsandsystemswithheteratomsubstitutionarepresented.Theroleofelectrocycli-
zationsinstereoselectivereactioncascadesishighlighted.
R1 R2 R1 R2
8π
R1 "con"
R2
(E,Z,Z,E)-octatetraene cyclooctatriene
R1 R2
6π
"dis"
H H
bicyclo[4.2.0]octadiene
R1 R2
6p
"dis"
H H
Keywords: asymmetriccatalysis•cyclobutenes•cyclohexadienes•cyclooctatrienes•
electrocyclization•electrocyclicringopening•Nazarovcyclizations•Woodward–Hoff-
mannrules•reactioncascades
p403
3.9 AllylicSubstitutionReactions
M.L.Crawley
Theallylicsubstitutionreactionhasevolvedfromalimitedprocessofprimarilyacademic
interesttoapowerfultoolfortheasymmetricformationofC-C,C-N,andC-Obonds.
Nu−
X a Nu
∗
ML n
R1 ML∗n R1 R1
R2 R2 b Nu− R2
Keywords: allylicsubstitution•asymmetricallylicalkylation•enantioselective•regio-
selective•transition-metalcatalysis
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Abstracts XV
p443
3.10 IsomerizationsToFormaStereogenicCenterandAllylicRearrangements
S.JautzeandR.Peters
Isomerizationsareoftenattractivereactionssincetheyprovidehighatomandstepecon-
omy.ThismanuscriptdescribesLewisacidcatalyzedorpromotedenantioselectiveisom-
erizations to form one or more stereogenic centers with a special focus on allylic rear-
rangements.
R2 Y Lewis acid R2 Y
X Z [3,3]-rearrangement X Z
R1 R1
Lewis acid
R2 Z [1,3]-rearrangement R2 Z
R1 R1
Keywords: allylicamines•allylicrearrangement•aza-Claisenrearrangement•aza-phos-
pha-oxa-Coperearrangement•Carrollrearrangement•Claisenrearrangement•imidates•
isomerization•Lewisacidcatalysis•Meerwein–Eschenmoser–Claisenrearrangement•
palladacycles•sigmatropicrearrangement•thia-Claisenrearrangement•Wagner–Meer-
weinrearrangement
p469
3.11 AllylicandBenzylicOxidation
M.B.Andrus
Theselectiveoxidationofalkenestogiveallylicalcoholsandtheirderivativesiscommon-
lyperformedusingseleniumdioxide.Conversionofalkenesintoallylicestersisalsofa-
cilitatedusingapalladium(II)acetatecatalystwithbenzoquinoneandwithcatalyticcop-
percomplexesusingperesteroxidants.Regio-andstereoselectivityarereliablycontrolled
throughproperchoiceofreagentoradditive,andbyvariationofthemetal/ligandcombi-
nation,butareoftendependentonthesubstrate.Enoneformationispromotedbyvari-
ousmetalcatalystswithtert-butylhydroperoxide,andbenzylicoxidationcanbeachieved
usingvariousmetalcatalystsandoxidantstogivebenzoylandbenzylalcoholmoieties.
Biocatalyticmethodshavealsobeendevelopedinalimitednumberofcases,usingcata-
lystsrelatedtometalporphyrincytochromeP450.C-Hactivationreactionsattheallylic
andbenzylicpositioncanthusbeemployedasanefficientapproachtotheinstallationof
oxygenfunctionalityatalatestageofamultistepsynthesisandusedasameanstocon-
structenantioenriched startingmaterials.This sectionillustrates thesetransformations
and examples are presented which demonstrate high levels of diastereo- and enantio-
selectivity.
O
[O]
[O]
O
Keywords: alcoholsynthesis•allylicoxidation•benzylicoxidation•C-Hactivation•
copper–peresteroxidation•enonesynthesis•ketonesynthesis•palladium–quinoneoxi-
dation•seleniumdioxide
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XVI Abstracts
p483
3.12 Mizoroki–HeckReaction
M.Shibasaki,T.Ohshima,andW.Itano
This manuscript covers both intermolecular and intramolecular Mizoroki–Heck reac-
tions (palladium-catalyzed arylation or alkenylation of alkenes) with brief discussion of
themechanisticaspectsrelevantforstereoselection.
R3 Pd(0) (cat.) R1 R3
base
R1X + − base•HX
R2 R4 R2 R4
R1 = aryl, alkenyl;
X = halide, pseudohalide
Keywords: alkenylation•arylation•enantioselectivity•palladiumcatalysts•phosphorus
ligands•regioselectivity
p513
3.13 C-CBondFormationbyC-HBondActivation
H.M.L.DaviesandD.Morton
ThismanuscriptdescribestheC-Cbond-formingreactionsthatareavailableviaC-Hac-
tivation.Itprovidesanoverviewofthemanydevelopmentsinthisfield,highlightingthe
mostefficientapproachesandtheirapplicationtorelevanttargets.
R3
R4
H
R1 N2 R1 R5 H R3R4
R2 N2 R2 MLn R1 R2 R5
metal carbenoid
C−H functionalization
MLn MLn
R3
R3 oxidative addition R4
R4 C−H activation X
H R3 H R5
R5 R4
MLn X
R5
Keywords: carbenoids•carbocycliccompounds•C-Cbondformation•C-Hactivation•
chiralcompounds•diazocompounds•rhodiumcomplexes•rhodiumcatalysis•palladi-
umcomplexes•palladiumcatalysis
p567
3.14 CrossCoupling
M.ShimizuandT.Hiyama
Transition-metal-catalyzed cross-coupling reactions of organometallic reagents with or-
ganic (pseudo)halides have been developed to become one of the most powerful and
straightforwardmethodsforC-Cbondformationavailable.Thissectionfocusesonthose
cross-coupling reactions that provide versatile solutions for a variety of stereochemical
issuesinmodernorganicsynthesis.
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Abstracts XVII
Ni catalyst or Pd catalyst
R1M + R2X R1 R2
Keywords: alkenylation•alkylation•alkynylation•allylation•asymmetricsynthesis•
boroncompounds•cross-couplingreactions•Grignardreagents•nickelcatalysts•palla-
diumcatalysts•siliconcompounds•tincompounds
p615
3.15 Protonation,Alkylation,Arylation,andVinylationofEnolates
B.M.StoltzandJ.T.Mohr
In this manuscript methods for enantioselective functionalization of enolates are re-
viewed, and strategies for controlling enolate formation, geometry, and steric environ-
ment are highlighted. The transformations discussed include protonation, alkylation,
arylation, and vinylation of enolates. Enantioselective protonation methods including
biocatalytic, stoichiometric, and catalytic processes are discussed. Chiral auxiliaries for
alkylation,includingacyclicandcyclicenolates,arecompared.Othertechniquesforcon-
trollingenolatealkylation,suchaschelationofthecounterionorgenerationoftransition
metal enolates in situ, are analyzed. Enolate arylation with chiral auxiliaries or chiral
transition-metalcatalystsisreviewedandtheprocessescompared.Vinylationofenolates,
includingveryrecentdevelopments,isdiscussed.Themethodscoveredprovideanover-
view of the available transformations for functionalizing carbonyl compounds via the
correspondingenolates.Syntheticapplicationsarehighlightedtoshowtheutilityofthe
techniquesdescribed.
O O
R3 R3
R1 R1
R2 protonation alkylation R4 R2
O
R3
R1
arylation vinylation
R2
O O
R3 R3
R1 R1
Ar1 R2 R2
Keywords: asymmetriccatalysis•chiralauxiliaries•chiralligands•crosscoupling•
enantioselectivealkylation•enantioselectivearylation•enantioselectiveprotonation•
enantioselectivevinylation•enolates•nickelcatalysis•palladiumcatalysis
p675
3.16 Æ-FunctionalizationofCarbonylCompounds
D.W.C.MacmillanandA.J.B.Watson
ChiralamineorganocatalystsenablethefacileasymmetricÆ-functionalizationofcarbon-
ylcompounds.Undertheenamine,SOMO,andphotoredoxcatalysisplatforms,C-Cand
C-X bonds (where X = heteroatom) can be forged, providing access to a broad range of
enantioenrichedproducts.
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