Literature Seminar (D2 part)

071114 (wed)

Wataru Itano (D2)page 1

Cationic Phosphine-Gold(I) Catalysis for C-C Forming Reaction with C C~ Can relativistic effects rationalize its reactivity? ~@ Carbometallation is powerful C-C bond formation although stoichiometric metal is needed.
Nu M

NuE

M

NuE

(M = Li, MgX, Cu, Zr etc.)
outstanding example
LHMDS. THF/tol 1/1, -78°C;
tBuLi (4 eq); AcOH

A.G. Myers et al.
(JACS 2006 14825)

30-40%@ Catalytic variant of this transformation is highly attractive
Nucat. M

ENu EElectorophilic late transion-metals (easily forming π-complex) might be suitable for Nu addition.
But standard carbon Nu (enolate etc.) is difficult to apply(oxi./red. stable but electrophic metal
problem : oxidative coupling of substrate etc.

is desirable)

Recently some transition metal catalysts (InIII, AuI or III, PdII etc) are realized for this carbon Nu addition.
I
Among them, [R3P-Au ]is one of the most powerful catalysts.

-1995

F. Dean Toste

B.Sc. and M.Sc. / University of Toronto, Canada (Prof. Ian W. J. Still)

1995-2000

Ph.D. / Stanford University (Prof. Barry M. Trost)· asymmetric alkylation (Pd), cycloisomerization (CpRu+), some total syntheses· 21 papers (17 JACS ! )2001-2002

Post-Doctoral Fellow / Caltech (Prof. Robert H. Grubbs)

2002-2006

Assistant Professor / University of California, Berkeley

2006-

Associate Professor / University of California, Berkeley（相対論的効果）?

?

He utilizes relativistic effect to explain unique reactivities of gold.
D. J. Gorin and F. D. Toste (Nature 2007, 446, 395-403)< Contents >0. Preface(p2)1. Thoretical chemistry of Gold1-1. Relativistic effects(p3)
1-2. Other theoretical aspects (p4)

3. Reaction after Nu addition (via carbenoid)
3-1. Generation of cationic intermediates
3-2. Investigation of cationic intermediate

2. Nu addition toward C=C
2-1. Heteroatom Nu(discovery of [R3PAu(I)]+)
2-2. Theoretical chemistry of cationic phosphineGold(I)2-3. Carbon Nu(Au(I) vs Au(III))

(p5)
(p6)
(p7-8)(p9)(p10)

0. Preface

Group 11

Au --- [Xe] 4f145d106s1> Au(AuI --- [Xe] 4f145d106s0 )(Z = 79)

AuI(d10)

AuI X

LPeriod 6

L (σ-donator)?

L (π-acceptor)

page 2CuAg
Ir Pt Au Hg

L

AuIII(d8)14elinear, two-coordinate

AuIIIXX
16e

X

planar, tetra-coordinate> intrinsically π-electrophilic
first recognized in heterogeneous catalyst
G. J. Hutchings (J. Cat. 1985, 96, 292.)(H-OR, H-NR, H-Ar)

then extend homogeneous catalyst

O(Na[AuCl4], AuCl3, AuCl)

Nu =O
ORR(Toste`s initial work on Gold)[Au] = cationic phosphine-gold(I)(His understanding from experiments)

1. strong Lewis acidity (compared with other π-electrophilic late transition-metals)
AuI

R 3PX

2. potential to stabilize cationic intermediate> Relativistic effect (量子化学の世界において相対性理論を加味した場合に出てくる効果…らしい）
should be considered when investigating (calculating) the electronic structure of heavy atoms (> 5th-row)(stabilized energically)

In Au (Z = 79),
relativistically expected

1. contracted 6s orbitals

LUMOin Au(I)

explains these characters.

2. expanded 5d orbitals(destabilized energically)
HOMO> To simplify Toste`s work(with alkyne)"alkynophilic acid"

Au
1NuE

Nu E

4Au

Ein Au(I)direct additionof carbon Nu to alkyne(see section 2)

Nu

Au 2

3Au

Nu
E 5 Aurelativistic 6s contraction
explains Lewis acidity

E(hopefully)

generation offurther intermediate;functionalization(see section 3)

relativistic 5d expansion
might stabilize further intermediate(functionalizationof carbenoid)

product
Au

NuE

6Au

(Au-carbenoid ?)1. Theoritical chemistry of Goldpage 3

1-1 Relativistic effects> quantum mechanics + special relativity
Schrodinger`s equation(speed of light : c is infinite)

molecular orbital calculation

structure of electrons· the average radial v of the 1s electrons

v = Z au

In heavy atom (Z > 4-50), v has significant value relative to c

Z: atomic number(c = 137 au)

considerationof special relativity

Dirac`s equation(c is finite)

The term "relativistic effects" refers to any phenomenon resulting fromthe need to consider velocity as significant relative to the speed of light.

> one basic consequense of special relativity
m: corrected mass
m0: non-relativistic (rest) mass

mmass increases towards infinity as a body's v approaches c> effects
Effect 1: The Relativistic Contractionmが相対論的効果で増加
a0は減少

Bohr radius:(supported by caclulation)(expected r for valence s)r [au]Cu(4s)

Ag(5s)

Au(6s)

3.2

3.4

3

P. Pyykko et al. (Acc. Chem. Res. 1979, 276.)

P. S. BAGUS (Chem. Phys. Lett. 1975, 408.)· contraction of the 1s andall s and p orbitals.

Stabilization of orbital energies

why Au so contracted
around Z ~80 ?
78Pt

80Hg

Practically, contraction is only significant
for elements in which the 4f and 5d orbitals are filled· electrons are closer to the nucleus;
have greater ionization energies.
(supported by caclulation)

HF (non relativistic)
DHF (relativistic)ps (non lanthanide)(experimental values)

page 4

Effect 2: The Relativistic Self-Consistent Expansion
The d and f orbitals are not contracted. (higher angular momentum, seldom descend to nucleus)
better shielded by contracted s and p orbitals
Instead,see a weaker nuclear attraction
Destabilization of orbital energies

Expansion of d and f orbitals
Effect 3: The Spin-Orbit splittingAu

relativisticeffects

6s orbitals contracted

stabilizing

5d orbitals expanded

destabilizing (and spliting)> these effects are reflected in MO calculation
P. Pyykko et al. (Acc. Chem. Res. 1979, 276.)

1-2 Other theoretical aspects> aurophilicity
the tendency for Au–Au interactions to be stabilizing on the order of hydrogen bonds(might be important for neutral complex (LAgX etc..))> [Me2AuI]
not particularly nucleophilic relative to the corresponding CuI (and AgI) complexes.
E. Nakamura et al. (J. Am. Chem. Soc. 2005, 127, 1446.)> Me2RAuIIIL (R = Me or allyl, L = PMe3)
reductive elimination is relatively disfavoured as well.
AuI and AuIII complexes do not readily cycle between oxidation states.
(of course exception exists)( + from experiments)
tolerate both oxygen and acidic protons,@ With its unique properties strongly influenced by relativistic effects,
theoretical chemists have much attention to gold.
review P. Pyykko (Angew. Chem. Int. Ed. 2004, 43, 4412.)(pp 4424)one can regard the moiety [AuPR3]+ as a σ-acceptor in analogy to H+.

2. Nu addition toward C

page 5Creview

quite a lot !

A. S. K. Hashmi (Angew. Chem. Int. Ed. 2005, 44, 6990-6993)
A. S. K. Hashmi and G. J. Hutchings (Angew. Chem. Int. Ed. 2006, 45, 7896-7936)
A. S. K. Hashmi (Chem. Rev. 2007, 107, 3180-3211)
D. J. Gorin and F. D. Toste (Nature 2007, 446, 395-403)

2-1 Heteroatom Nu> initially AuIII halide(intermolecular)(intramolecular)(anhydrous)

6-exo-dig@ PdII unsatisfactory results@ internal --- regio mixture, terminal --- Markovnikov@ K[Au(CN)2] is inactive@ Na[AuCl4] quickly reduced to metalic Au (TON >50)

Utimoto. K. et al. (Heterocycle. 1987, 96, 292.)

Utimoto. K. et al. (J. Org. Chem. 1991, 96, 292.)> cationic phosphineAuIJ. H. Teles et al. (Angew. Chem. Int. Ed. 1998, 37, 1415)
in situ generation of [L-AuI]+

MeH(continuous streaming)+MeOH

Ph3PAuMe (X mol%)
MeSO3H (10X mol%)(1 eq)

20-50 °C

MeOOMe< terminal alkyne >less steric hinderance for Au(Markovnikov)

IITON up to 50000! (0.00002 mol%), TOF up to 5400 h-1 (cf Hg quickly reduced to metalic Hg (TON ~100))[L-AuI]+

the initial TOFs [h-1] : Ph3As (430) < Et3P (550) < Ph3P (610) < (4-F-C6H4)3P (640) < (MeO)3P (1200) < (PhO)3P (1500)
electron-poor ligands lead to an increase in activity, but the stability decreases.

[Ph3PAuIX]

the initial TOFs [h-1] : I- (2) < Cl- (7) < NO-3 ~ CF3COO- ~ CH3SO-3 (700)progresses from soft to hard anions< internal alkyne >less steric hinderance for MeOH+@ experimental data

@ Ab initio calculation

cis-auration

intuitively trans-auration acceptable

1,3 hydrogen migration;bond rotation

theoretically cis-auration

2-2 Theoretical chemistry of cationic phosphineGold(I)> [R3PAuI]+ + PH3
far more covalentrobust1)
in reaction[H3P

2nd PH3 isAuI]
2)

page 6

Au(I)+ is a large, diffuse cation sharing positive charge
with the phosphine ligand,
one might expect orbital rather than charge interactions
in binding a second ligand.

"soft"

PH36s orbital of [R3PAuI]+can further accept electrons (contracted 6s)
keep strong Lewis acidity

AuCl[X2AuIII]+

not investigated+ PH3

P. Schwerdtfeger et al. (Inorg. Chem. 2003, 42, 1334.)> Stability of [R3PAuI]+ + L
1) with several ligand

J. H. Teles et al. (Angew. Chem. Int. Ed. 1998, 37, 1415)

stability [kJ/mol]:[Me3PAuI]+ + L

CH2Cl2 (+63) < H2O (+44) < acetylene (+38) < MeOH ~ 1,4-dioxane (+24)< propyne (+18) < THF (+2) < 2-butyne (0) < Me2S (-18 ) < Ph3P (- 114)

carbophilic rather than oxophilic

substituted alkynes are better ligands than MeOH or dioxane

W. Koch et al. (J. Phys. Chem. 1996, 100, 12253)
V. M. Rayon et al. (J. Phys. Chem. A 2004, 108, 3134)

2) alkyne vs alkene
Experimentally, reactivity of Nu is>but theoretical stability is inverse

E(Au+-alkyne) < E(Au+-alkene)(~10 kcal/mol)

alkynes LUMOs intrinsically lower than alkenes (~0.5eV)That is important for Nu addition.
LL> Backdonation from [R3PAuI]+1) to alkyne /alkene (by calculation)
Backbonding to antibinding orbital (of alkene / alkyne) is poor (smaller than Cu)
render alkyne / alkene more electron deficient2) to carbene (their explanation, not by calculation ?)Backbonding to antibinding orbital also might be poor
but backbonding (from AuI 5d) to lower-energy (than antibonding) non-bonding p-orbitals(of carbene) might be suitable
relativistically expanding(destabilizing)
This can stabilize carbenoid intermediate in the AuI catalyzed reaction

2-3 carbon Nu

page 7> (Nu = β-keto ester)(J. Am. Chem. Soc. 2004, 126, 4526)

5-exo-dig

terminal alkyne only

cationic - AuI - mono-phosphine#1 [AgI]+ weak Lewis acidity#2 [R3PAgI]+ insufficient#3 [AuIIIX3] sufficient Lewis acidity (?) but undesired path
#4 [R3PAuIX ]?
Au vs Ag --- relativistic contraction of s orbital? [AuI]+ vs AuI --- aurophilicity (?)?
AuI vs AuIII --- unknown (for regio , see (Nu = Ar-H))?
Au vs Pt --- not mentioned (possible?)insufficient#5 [R3PAuI]+ sufficient Lewis acidity#6 [(RNC)2AuI]+ insufficient

nucleophilic attack on a Au(I)-alkyne complex by enol

trans-auration

cis-auration
formation of a Au-enolate followed by a cis-carboauration

HD

[Au]

[Au]

H

D

Now generally accepted.

Trans-auration(mechanism A)

MeO2C

5-endo-dig (Angew. Chem. Int. Ed. 2004, 43, 5350)(1,5-enyne)> usually prepared in situ

MeOHR

[AuI]+5-endo-dig

MeO2CMeOinternal alkyne OKR

R3PAuICl + AgIX

[R3PAuI] X

R3PAuIMe + HX

(X = OTf, SbF6, BF4 etc)[(R3PAuI)3O]X + HX

(L = R3P)

page 8> (Nu = Ar-H)@ Regioselectivity is inversed between Au(I) and Au (III) with terminal alkyne,(only intrinsical regio ?)M. T. Reertz et al. (Eur. J. Org. Chem. 2003, 3485)n+[Au(III)][LAu(I)]+(10 eq)(10 eq)+(Z/E = 100/0)

AuCl3 / 3AgBF4 (5 mol%)
60°C, 16h

Ph3PAuCl/AgBF4 ineffective

37 (~60%) + 39 (10%)(Z/E = 78/22)Au(III) slightly activate carbonyl ?
@ Ar-[Au] might be unlikely instead of electrophilic activation of alkyne(2 eq)
2,6-lutidine[AuCl3]2HPh

THF
50°C, 5h82-94%

unstable

Y. Fuchita et al. (J. Chem. Soc., Dalton. Trans. 2001, 2330)> AuI vs AuIII (Nu = -C=O)@ They said "oxophilic AuIII species" and "π-philic AuI species"(or AuCl3 + THF)

[Au(III)][LAu(I)]X
H

1,2 hydride shift
via gold carbenoid

V. Gevorgyan et al. (J. Am. Chem. Soc. 2005, 127, 10500)Basically both Au(I) and Au(III) are π-philic
But Au(III) is slightly more oxophilic than Au (I)(my opinion)(summary so far)

Nu

Nu

E2 Au
a lot !

3How to generate
vinyl-Au

Au(R1 = E) (endo/exo)

R2Nu

7R

Au

E
(R2 = E)
(endo/exo)E(Nu = S, E = allyl, silyl etc.)Nuseveralelectrophiles

9E

same
position

Nu

R

11

Y. Yamamoto et al.
(Angew. Int. 2006, 45, 4473.)(OL. 2007, 9, 4081.)

L. Zhang(JACS 2005, 127, 16804)

NuEAu

This section(Nu = N, O, C, E = H)

(Nu = O, E = benzyl, iminium)

RE10Au8Nu4sameposition

ENu

R1NuE

Au

12

F. D. Toste et al.
intramolecular carboalkoxylation(JACS. 2006, 128, 12062)

different position
Nu

Next section(Toste`s plan)

E3

Au

Nu

Nu
E

5 Au

E6Au

relativistically expanding 5d orbitals of Au
might stabilize cationic intermediate by backdonation

new reaction ?

3. Reaction after Nu addition (via carbenoid)

page 9different position
NuE

Nu

2 Au

3

NuNuEAuE

5 AuEAu

63-1 Generation of cationic intermediates@ AuI-NHC complexes are known

can catalyze cyclopropanation of styrene with ethyldiazoacetate
S. P. Nolan et al.
(Angew. Chem. Int. Ed. 2005, 44, 5284)@ vinyl Au species was proposed to have significant Au carbene character on the basis of NMR, X-ray, and calculations
H. G. Raubenheimer et al.
(Organometallics 2002, 21, 3173)(E ---> Cr(CO)5)

cationic intermediate [56] might exists

different position
ENuendoEH

13AuE

Nu1,2H-migration

NuHH14E

NuAu

15 Au

ENu

H16AuAu

17@ initial work of Tostesame intermediates (14-16) was proposed with AuI(J. Am. Chem. Soc. 2004, 126, 10858)

complete conversion,
but substantial amount of decomposition.

Nieto-Oberhuber, C. et al.
(Angew. Chem. Int. Ed. 2004, 43, 2402)(Chem. Eur. J. 2006, 12, 1677.)
Furstner, A. et al.
(J. Am. Chem. Soc. 2004, 126, 8654)· 5% AuCl3 with 15% AgOTf

pseudoeqatrial(16)(1415)·Au might lower the barrier to cationic intermediateby backbonding.
stereospecific"expanded 5d"Anyway... carbenoid or cationic ?
·With Au(III), analogous intermediates were proposed.
·Pt(II) shows similar reactivity(relativistic effect also influense Pt)
activation of alkynes

cationic Au(I) --- even in the presence of strongly donating ligands, such as phosphines
reactivity tuning, stereoselectivity
Pt(II) --- simple salts or CO complex

page 10

3-2 Investigation of cationic intermediate
different position
RRNuOE

Nu

Nu

NuO

5-exoAu18OOEAu

RREAu19

C-C bond formation

EAu

20

21
(J. Am. Chem. Soc. 2005, 127, 5802)

Original
Rautenstrauch rearr.

(J. Org. Chem. 1984, 49, 950)

metal carbene intermediate proposed"a method for generation of metal-carbenoid"

Toste`s casechirality transfer
not Au-carbene (21)A. R. de Lera (J. Am. Chem. Soc. 2006, 128, 2434)= (19)

DFT calculation predicts
helically chiral intermediate

cyclization from cationic vinyl-Au (9 or 11)
might predominate

Nazarov likecyclization(20) =carbenoid or cationic ?
= (19)

cationicon a fast time scale(intramolecular reaction)= (21)

toward highly carbenoid character(J. Am. Chem. Soc. 2005, 127, 18002)

cis favored1)
stereochemical information
was not conserved.

"carbenoid"

might be concerted mechanism

page 11
R
PivO

2)
R'Au

3)

L

Ar'R

Ar'
high ee even linear geometry of Au

PivO

IAr

X

Anyway...
carbenoid character might dominatesAu
L

further reaction would be developed.

R'Au

Au

Au
L

bifunctional ?
LLdicationic ?

mono cationic ?

> to conquar demerit of linear coodination geometry of AuI for ee(Science. 2007, 317, 496)

5-exo
@ standard chiral phosphine poor ee (<10%ee)@ only PPh3AuCl or Ag-6 or

H : no rxn@ dinuclear AuI better@ less polar solvent best
ee depends on the proximity of the counteranion
to the cationic gold center(+H+: known as chiral Bronsted acid catalyst)@ match-mismatch pairing between chiral phosphineand chiral counteranion observed in other systems.
might extend standard transition metal catalysed processcf) hydroamination of allene with chiral phosphine gold(J. Am. Chem. Soc. 2007, 129, 2452)

AuI< summary >6s contraction

strong Lewis acidity

5d expansion

backdonation for carbenoid(Nature 2007, 446, 395-403)

carbon Nu(with alkyne)

Conia-Ene (JACS 2004, 126, 4526) (Angew 2004, 43, 5350)
Silyl-enol (Angew 2006, 45, 5991)

E

How to generate
propalgyl claisen. (JACS 2004, 126, 15978)
ring expansition (JACS 2005, 127, 9708)
etc.

Nu
Au

E

Nu

4Au

Nu

alkoxycarbolation (JACS 2006, 128, 12062)

How to generate
Au

How to proceedcarbon E

acetylenic Schmidt (JACS 2005, 127, 11260)
cyclopropanation (JACS 2005, 127, 18002)

32

E

different mode

cycloisomerization (JACS 2004, 126, 10858)
Rautenstrauch rearr.(JACS 2005, 127, 5802)

ENuNu

EE

1,2-shift, cyclization
rearrangement etc..

product
5 Au

6Au
oxidative trap
(JACS 2007, 129, 5838)(with allene)
other works about Au(cycloaddition)(asymmetric variants)