Organic Reaction Mechanisms · 2006: An annual survey covering the literature dated January to December 2006

591 Pages·2010·5.356 MB·English

·
ORGANIC REACTION MECHANISMS 2006
Organic Reaction Mechanisms · 2006: An annual survey
covering the literature dated January to December 2006
Edited by A. C. Knipe
© 2010 John Wiley & Sons, Ltd. ISBN: 978-0-470-51905-9
ORGANIC REACTION
·
MECHANISMS 2006
An annual survey covering the literature
dated January to December 2006
Editedby
A. C. Knipe
University of Ulster
Northern Ireland
®
AnInterscience Publication
A John Wiley and Sons, Ltd., Publication
Thiseditionfirstpublished2010
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Contributors
S.K. ARMSTRONG Department of Chemistry, University of Glasgow,
Glasgow, G12 8QQ, UK
K.K BANERJI Indra-Kripa, A-80 SaraswatiNagar, Jodhpur 342005,
INDIA
C.T. BEDFORD Department of Chemistry, University College Lon-
don, 20 Gordon Street, London, WC1H 0AJ
M.L. BIRSA Department of Chemistry, Al I Cuza University of
Iasi, Bd. Carol I, 11, Iasi 700506, Romania
A. BRANDI Dipartimento di Chimica Organica “U. Schiff”, Uni-
versita’ degli Studi di Firenze-Polo Scientifico, Via
della Lastruccia 13 1-50019 Sesto Fiorentino (Fl),
Italy
M. CHRISTLIEB Gray Institute for Radiation Oncology and Biol-
ogy – University of Oxford, Old Road Campus
Research Building, Churchill Hospital, Oxford, OX3
7DQ
R.G. COOMBES Honorary Research Fellow, Department of Chem-
istry, University College London, 20 Gordon Street,
London, WC1H 0AJ
M.R. CRAMPTON Chemistry Department, The University, South Road,
Durham. DH1 3LE
N. DENNIS University of Queensland, PO Box 6382, St. Lucia,
Queensland 4067, Australia
E. GRAS CNRS, LSPCMIB Universite Paul Sabatier, 31062
Toulouse Cedex 9, France
P. KOCˇOVSKY´ Department of Chemistry, The Joseph Black Build-
ing, The University of Glasgow, Glasgow G12 8QQ
R.A. McCLELLAND Department of Chemistry, University of Toronto, 80
StGeorgeStreet,Toronto,Ontario,M5S1A1,Canada
B. MURRAY Department of Science, IT Tallaght, Dublin 24,
Ireland
K.C. WESTAWAY Dept. of Chemistry and Biochemistry, Laurentian
University, Sudbury, Ontario P3E 2C6, Canada
v
Preface
Thepresentvolume,theforty-secondintheseries,surveysresearchonorganicreaction
mechanismsdescribedintheavailableliteraturedated2006.Inordertolimitthesizeof
thevolume,itisnecessarytoexcludeorrestrictoverlapwithotherpublicationswhich
review specialist areas (e.g. photochemical reactions, biosynthesis, electrochemistry,
organometallic chemistry, surface chemistry and heterogeneous catalysis). In order to
minimize duplication, while ensuring a comprehensive coverage, the editor conducts
a survey of all relevant literature and allocates publications to appropriate chapters.
While a particularreference maybe allocatedto more thanone chapter,it is assumed
that readers will be aware of the alternative chapters to which a borderline topic of
interest may have been preferentially assigned.
In view of the considerable interest in application of stereoselective reactions to
organicsynthesis,wenowprovideindication,inthemargin,ofreactionswhichoccur
with significant diastereomeric or enantiomeric excess (de or ee).
Unfortunately the personal circumstances of an author resulted in an unexpected
delay in publication of this volume, for which we apologise. The next volume is
expected to be published in the same year and steps have been taken to ensure that
the delay between title year and publication date will be further reduced thereafter.
I wish to thank the production staff of John Wiley and Sons and the team of
experienced contributors for their efforts to ensure that the review standards of this
series are sustained.
vii
CONTENTS
1. Reactions of Aldehydes and Ketones and their Derivatives
by B. A. Murray..................................................... 1
2. Reactions of Carboxylic, Phosphoric and Sulfonic Acids and their
Derivatives by C. T. Bedford......................................... 53
3. Oxidation and Reduction by K. K. Banerji............................ 91
4. Carbenes and Nitrenes by M. Christlieb and E. Gras................... 153
5. Nucleophilic Aromatic Substitution by M. R. Crampton............... 175
6. Electrophilic Aromatic Substitution by R. G. Coombes................ 187
7. Carbocations by R. A. McClelland.................................... 203
8. Nucleophilic Aliphatic Substitution by K. C. Westaway................ 231
9. Carbanions and Electrophilic Aliphatic Substitution
by M. L. Birsa....................................................... 277
10. Elimination Reactions by M. L. Birsa................................. 307
11. Addition Reactions: Polar Addition by P. Kocˇovsky´ .................. 317
12. Addition Reactions: Cycloaddition by N. Dennis...................... 379
13. Molecular Rearrangements: Part 1. Pericyclic Reactions
by S. K. Armstrong................................................... 419
14. Molecular Rearrangements: Part 2. Other Reactions
by A. Brandi and M. Gensini.......................................... 451
Author Index........................................................ 513
Subject Index....................................................... 549
ix
CHAPTER 1
Reactions of Aldehydes and Ketones
and their Derivatives
B.A.MURRAY
Department ofScience,Institute ofTechnology Tallaght (ITTDublin),
Dublin, Ireland
Formation and Reactions of Acetals and Related Species . . . . . . . . . . . 2
Reactions of Glucosides and Nucleosides . . . . . . . . . . . . . . . . . . . . 3
Reactions of Ketenes and Ketenimines . . . . . . . . . . . . . . . . . . . . . 3
Formation and Reactions of Nitrogen Derivatives . . . . . . . . . . . . . . . 3
Imines: Synthesis and Tautomerism . . . . . . . . . . . . . . . . . . . . 3
The Mannich Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Addition of Organometallics . . . . . . . . . . . . . . . . . . . . . . . . 6
Other Alkylationsand Allylationsof Imines . . . . . . . . . . . . . . . 7
Reduction of Imines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Iminium Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Other Reactions of Imines . . . . . . . . . . . . . . . . . . . . . . . . . 10
Oximes, Hydrazones, and Related Species . . . . . . . . . . . . . . . . 13
C–C Bond Formation and Fission:Aldol and Related Reactions. . . . . . . 14
Stereoselective Aldol Reactions Using Proline Organocatalysts . . . . . . 14
Other Stereoselective Aldol Reactions . . . . . . . . . . . . . . . . . . . 16
Mukaiyama and VinylogousAldols . . . . . . . . . . . . . . . . . . . . 18
The Aldol-TishchenkoReaction . . . . . . . . . . . . . . . . . . . . . . 19
Nitro and Nitroso Aldols. . . . . . . . . . . . . . . . . . . . . . . . . . 19
Other Aldol-typeReactions . . . . . . . . . . . . . . . . . . . . . . . . 20
The Aza and MoritaVariants of the Baylis–Hillman Reaction . . . . . . 21
Allylation and Related Reactions . . . . . . . . . . . . . . . . . . . . . 22
Olefinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Alkynylations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Michael Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Other Addition Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
General and Theoretical . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Addition of Organozincs . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Addition of Other Organometallics, Including Grignards . . . . . . . . . 29
The Wittig and Aza-Wittig Reactions . . . . . . . . . . . . . . . . . . . 30
Hydrocyanation, Cyanosilylation,and Related Additions . . . . . . . . . 30
Hydrosilylationand Related Reactions . . . . . . . . . . . . . . . . . . 32
Miscellaneous Additions . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Enolization and Related Reactions . . . . . . . . . . . . . . . . . . . . . . . 36
α-Halogenation, α-Alkylation,and Related Reactions. . . . . . . . . . . 37
Organic Reaction Mechanisms · 2006: An annual survey
covering the literature dated January to December 2006
Edited by A. C. Knipe
© 2010 John Wiley & Sons, Ltd. ISBN: 978-0-470-51905-9
1
2 OrganicReactionMechanisms2006
Oxidation and Reduction of Carbonyl Compounds . . . . . . . . . . . . . . 38
Regio-, Enantio-,and Diastereo-selectiveReduction Reactions . . . . . . 38
Other Reduction Reactions. . . . . . . . . . . . . . . . . . . . . . . . . 41
OxidationReactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Other Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Formation and Reactions of Acetals and Related Species
Chemoselectivities in the acetalization of p-nitro- and p-hydroxy-benzaldehyde have
been studied for a range of bisnucleophiles, XCH CH Y (X, Y = OH, OH; SH, SH;
2 2
SH,OH;andSH,NH).1 Therelativeyieldsofproductshavebeenanalysedintermsof
atomic charges, Parr’s global electrophilicity descriptor (w), and Pearson’s hard–soft
acid–base concept; such a global electrophilicity descriptor has also been used to
explain acetalizations and thioacetalizations of substituted benzaldehydes, although it
cannot handle steric factors.2
Pd[(−)-sparteine]Cl catalyses the conversion of styrenes to their Markovnikov
2
dialkylacetals.3 Deuteriumlabellingstudiessuggestanenolethermechanisminvolv-
ing a Pd–H species.
TheEberlinreaction–polaracetalizationandtransacetalizationinthegasphase–has
beenreviewed(249references).4Inadditiontoadetailedmechanistictreatment,several
analytical applications are described, as are atmospheric pressure variants, relation-
shipswithcondensed-phasereactions,andothergas-phaseprocessescloselyrelatedto
acetalization.Anotherreviewcoverssimilarground.5
(cid:2)
Enantiopure 1,6-dioxaspiro[4.4]nonanes [e.g. (1)] have been prepared from an de
α-hydroxy-ω-ene ketone, using a camphor–selenide auxiliary.6 (cid:2)ee
OH OP O O O O OP OH
O O
(1) (2)
Differentiation of 1,3-anti- and -syn-diols has been achieved via the selective
(cid:2)
hydrolysis of an anti-1,3-acetonide (2) containing an adjacent syn-acetonide.7 de
Gallium(III) chloride catalyses two useful reactions that employ isocyanides as a
C source:(i) aninsertionintoaC−Obondofanacetaland(ii)a4+1-cycloaddition
1
of α,β-unsaturated carbonyl compounds. The catalysis appears to depend on the low
affinity of GaCl for heteroatoms.8
3
The reagent BH .NMe –AlCl has been used to bring about reductive opening of
3 3 3
acetals.9 Withmixedphenolic–benzylicacetalasreactant,thereagentactsregioselec-
1ReactionsofAldehydesandKetonesandtheirDerivatives 3
◦
tively (in THF at 0 C), yielding a benzylic ether and free phenol, probably because
the borane first associates with the more basic benzylic oxygen. Conditions to bring
about the inverse opening are being sought.
Reactions of Glucosides and Nucleosides
A detailed experimental and computational study of the anomerization of glucose
in water has been undertaken.10 Following measurement of kinetic isotope effects
(KIE) on rate constants for approach of α-glucopyranose to its equilibrium with the
β-anomer, these were converted into unidirectional KIEs using equilibrium isotope
effects.Saturation transfer13C NMRspectroscopythenyieldedthe relative freeener-
gies of the transition states (TS) involved. Modelling, constrained by all the KIEs
measured,thengavetheanomerizationTSs.Keyfindingsincludetheobservationthat
only one water molecule is required to participate, and that it must not hydrogen
bridge OH(1) and O(5) simultaneously in either TS.
ThemechanisticroleofnucleotidesindirectingthegrowthofIR-emittingsemicon-
ductor nanocrystals has been investigated for a range of nucleotides, concentrations,
stoichiometries, and temperatures.11
Reactions of Ketenes and Ketenimines
A short review of the first 100 years of ketene chemistry covers haloketenes, Wolff (cid:2)
de
rearrangements, stereoselective nucleophilic attack, dimerization, cycloadditions,
ketene-Claisen and -Cope reactions, bisketenes, and free radical processes.12 (cid:2)ee
Two series of ketenimines, Ph–CH=C=N–Ph–p-R and p-R–Ph–CH=C=N–i-Pr,
havebeenaminatedwithbutylamine,withUVmonitoringallowingratemeasurement
and hence construction of Hammett plots for each ring system.13 Addition to the
C=N bond to give vinylidenediamine intermediate is followed by tautomerization
to amidine product. A switchover in rate-determining step is observed. Calculations
indicate that the N-aromatic group provides significant electronic stabilization to the
first TS.14
Formation and Reactions of Nitrogen Derivatives
Imines: Synthesis and Tautomerism
Erbium(III) triflate is an efficient catalyst in the synthesis of aldimines, ketoimines,
and enaminones.15 For aromatic imines, the problem of Michael addition found with
the CeCl /NaI-catalysed addition to unsaturated aldehydes is avoided.
3
An N-phosphinoylhemiaminal (3) has been used as a precursor to trifluoromethyl-
ketimines (4); insitu alkylation with a dialkylzinc in the presence of a diphosphine
monoxide auxiliary gives chiral α,α,α-trifluoromethylamines (5) in high yield and ee
up to 99%.16
4 OrganicReactionMechanisms2006
O O O
Ph Ph Ph
P P P
HN Ph N Ph HN Ph
Ar OEt Ar CF3 Ar R
CF CF
3 3
(3) (4) (5)
TheSkraup–Doebner–VonMillersynthesisofquinolines – involvingcondensation
of an aniline with an α,β-unsaturated ketone – has been investigated using 13C-
labelled ketones in cross-over experiments: a complex fragmentation–recombination
mechanism involving imine intermediates is indicated.17
Inanothersynthesisofquinolinesinvolvingimineintermediates,o-oxazoline-substi-
tuted anilines (6) react with ketones in dry butanol reflux to give 4-amino-substituted
quinolines [e.g. (7)], or 4-quinolones, using tosic acid as catalyst.18 A mechanism
involving ketoimine formation with subsequent tautomerization to give an enamine
which attacks the oxazoline ring is discussed.
A related one-pot, three-component synthesis of β-amino carbonyl compounds has
been achieved using a cascade reaction of anilines with aromatic aldehydes and car- (cid:2)
de
bonyl compounds, catalysed by zinc triflate.19
R2 R2 R3 O
R3
NH2 N HN OH
R1 OH OH
O
PhCHO O
N Ph
R1
(6) (7) (8)
Anenantioselectiveone-pot,three-componentimino-Reformatskyreactionhasbeen
reported.20 Combining a benzaldehyde, an aniline, and an alkyl bromoacetate ester, (cid:2)ee
eesofupto92%havebeenachievedintheβ-aminoesterproduct,usingarecyclable
N-methylephedrine asauxiliary. A nickel(II) salt anddimethylzinc are employed:the
latter serves as dehydrating agent, reductant, and coordinating metal.
Thekineticsandmechanismofthereactionofglycylglycine21 andofvaline22 with
ninhydrin (8) have been studied in aqueous micellar media.
Cis–trans isomerization in benzylideneaniline (PhCH=NPh) has been found by
computationtoinvolveasingleTS,andconformersleadingtoeachisomerhavebeen
identified.However,kineticselectivityofthetwoconformersdependsonthereaction
dynamics.23