Homogeneous Gold Catalysis

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1 1 omogeneous Gold Catalysis ighly Efficient Functionalization of C C Multiple Bonds and Electron-ich C Bonds 1% 61% yield C Et 1% ( 3 P)AuTf CE, rt, 50 min 95% yield Et 2 C AuL Et Michael. Krout Stoltz Group Literature Talk May 30, :1 d.r. 8pm, 147 oyes utline 1. Introduction a. istory b. A few basics of Au chemistry c. Some Au(I) and Au(III) organometallic complexes 2. Additions of carbon nucleophiles to activated C C multiple bonds a. Catalytic asymmetric aldol b. Stabilized carbon nucleophiles c. earrangements/cycloisomerization d. enol synthesis e. Arene nucleophilic additions (C functionalization) 3. eteroatom nucleophiles (also assisted) a. ydration/hydroamination b. eterocycle synthesis c. Annulation/napthylketone synthesis Select Au background references: Puddephatt,. The Chemistry of Gold; E. L. Sevier Scientific Publication Co., Amsterdam, ashmi, A. S. K. Gold Bulletin 2004, 37, Parish,. V. Gold Bulletin 1997, 30, Parish,. V. Gold Bulletin 1997, 30, Parish,. V. Gold Bulletin 1998, 31, Gimeno, M. C.; Laguna, A. Chem. ev. 1997, 97, Grohmann, A.; Schmidbaur,. Comprehensive rganometallic Chemistry II, 1995; vol. 3 pp 1-56.

2 Introduction Brief istory of Gold (circa.

krennerite, pyrite and other sulfides (tellurides).

Elemental Gold is purified by extractive metalllurgy (using Cl2 sources) or by cyaniding: 4 Au 8

corrosives, but is readily oxidized by Cl2 or dissolved in aqua regia, forming one of the most

The most malleable element: 1 g can be beaten into a 1 m2 sheet (~ 230 atoms thick) Used in

Introduction Basic Principles of Gold Chemistry Au(I) and Au(III) are the most common oxidation

ligands (e.g. 3P and carbanions): F < C2 < Cl < Br < I < S < 3P < Ar < hard soft Propensity for

2 2 Introduction Brief istory of Gold (circa BC) Gold is found in many minerals, including: quartz, nagyagite, calaverite, sylvanite, krennerite, pyrite and other sulfides (tellurides). Also found in veins in rocks or by sifting river beds. Elemental Gold is purified by extractive metalllurgy (using Cl2 sources) or by cyaniding: 4 Au 8 ac a[au(c)2] Zn 4 a[au(c)2] 4 a 2 ac Zn(C)2 Au (s) Gold is stable to oxygen and most corrosives, but is readily oxidized by Cl2 or dissolved in aqua regia, forming one of the most common gold complexes, AuCl4 (chlorauric acid). The most malleable element: 1 g can be beaten into a 1 m2 sheet (~ 230 atoms thick) Used in jewelry, denstistry, electronics, photography,coins, etc. Introduction Basic Principles of Gold Chemistry Au(I) and Au(III) are the most common oxidation states of Gold, with Au(III) being most prevalent Au is a soft metal, and therefore prefers soft ligands (e.g. 3P and carbanions): F < C2 < Cl < Br < I < S < 3P < Ar < hard soft Propensity for strong trans effect and trans influence trans effect: ability of L to labilize L trans to itself, directing incoming ligands to the trans position (kinetic effect) 3P > Cl trans influence: ability of a L to weaken the M L bond trans to itself in the ground state of the complex (thermodynamic effect) trans to Cl : ~ C6F5 > 3P > SPr2 ~ Cl

3 Introduction Basic Principles of Gold Chemistry Au organometallic complexes have a very low tendency to undergo!- elmination; Au complexes are very rare.

3 3 Introduction Basic Principles of Gold Chemistry Au organometallic complexes have a very low tendency to undergo!- elmination; Au complexes are very rare. Protodemetallation extremely fast; it is proposed that the Au-ate complex is protonated by acid, followed by reductive elimination. Weaker acids react more slowly for protonolysis of the Au C intermediate. Ar AuL Ar Ar AuL intermediate? Au(I) and Au(III) ligand exchange reactions are associative, and can occur at extremely high rates. Although Au complexes can undergo oxidative addition/reductive elimination, these processes are rare except for a few well defined cases. The lack of oxidation state change makes coupling chemistry (think Pd) difficult. Many mechanims proposed with the following chemistry, but it is important to note that in many cases the mechanism, and even the oxidation state of the catalytically active species are not known. Au(I) Complexes Au(I) complexes are d 10 and prefer to be linear, two-coordinate can be 3-coordinate trigonal planar can be 4-coordinate tetrahedral AuCl commercially available source of Au(I); exists as a polymeric chain with µ-cl L's Cl AuCl Au Cl n bench stable, but can reduce to Au(0) slowly: AuCl v. slow Au(0) Au 2 Cl 6 3 P can dissociate to form monomeric ( 3 P)AuCl a[aucl 4 ] 2 3P ( 3 P)AuCl AuCl 4 S 2 Cl P ( 3 P)AuCl elv. Chim. Acta. 1973, 56, 2405 Inorg. Synth. 1986, 24, 236

4 4 Au(I) Complexes [( 3 PAu) 3 ]BF 4 common source of electrophilic Au(I); useful in organometallic synthesis air and moisture stable ( 3 P)AuCl Ag 2 abf 4 [( 3 PAu) 3 ]BF 4 LAu readily prepared from L-stabilized Au(I) halide; bench stable complexes LAu Li or Mg LAu [( 3 PAu) 3 ]BF 4 1. Li or Mg 2. 2 workup LAu Inorg. Chem 1993, 32, 1946 J. rganomet. Chem. 1989, 369, 267 Cationic Au(I) Complexes Common methods for generation of LAu: 1. Ag, where = non-coordinating anion 2. LAuC 3 strong acid (e.g. 2 S 4, Ms, BF 4 ) 3. LAu BF 3 Et 2 4. [(LAu) 3 ]BF 4 BF 3 Et 2

5 Au(III) Complexes Au(III) complexes are d 8 and prefer to be square planar, four-coordinate; best known oxidation state commercially available source of Au(III); exists as a dimer(au 2 Cl 6 ) with

5 5 Au(III) Complexes Au(III) complexes are d 8 and prefer to be square planar, four-coordinate; best known oxidation state commercially available source of Au(III); exists as a dimer(au 2 Cl 6 ) with µ-cl L's AuCl and aaucl the cheapest available source of Au(III) Au(0) aqua regia AuCl Et 2 or EtAc extraction 2. eutralize MAuCl M= a or K C C Bond Forming eactions Catalytic, Asymmetric Aldol C C 2 C 1% [Au(c-C 6 11 C) 2 ]BF 4 1% A C 2 Cl 2, 25 C h trans C 2 cis C 2 % yield trans/cis ratio %ee trans 98 89/ /16 72 c-ex 95 97/3 90 Fe P 2 P 2 2 t-bu /0 97 A Fe BF 4 2 P 2 Au C P 2 Proposed Transition State Model Ito, Y.; ayashi, T. JACS 1986, 108, 6405 Ito, Y. Chem. ev. 1992, 92, 857

6 C C Bond Forming eactions Catalytic, Asymmetric Aldol 6 C C 2 C 1% [Au(c-C 6 11 C) 2 ]BF 4 1% A C 2 Cl 2, 25 C h trans C 2 cis C 2 % yield trans/cis ratio %ee trans 98 89/ /16 72 c-ex 95 97/3 90 Fe P 2 P 2 2 t-bu /0 97 A 2 BF 4 trans/cis ratio %ee trans (C 2 ) /11 23 Fe P 2 Au C P 2 Fe P 2 P 2 (C 2 ) 2 69/ /32 racemic Proposed Transition State Model Ito, Y.; ayashi, T. JACS 1986, 108, 6405 Ito, Y. Chem. ev. 1992, 92, 857 C C Bond Forming eactions Catalytic, Asymmetric Aldol C C 2 C 1% [Au(c-C 6 11 C) 2 ]BF 4 1% A C 2 Cl 2, 25 C h trans C 2 cis C 2 % yield trans/cis ratio %ee trans 98 89/ /16 72 c-ex 95 97/3 90 t-bu /0 97 C 2 Cl C 2 2 Cl BF 4 2 P 2 Fe Au C P 2 Proposed Transition State Model LiAl 4 2 also see: Ito, Y.; ayashi, T. Tet. Lett. 1988, 29, 235 Lin, Y.-. Tet. Asymm. 1999, 10, 855

7 C C Bond Forming eactions Stabilized ucleophilic Addtions to Alkenes % AuCl 3 15% AgTf 3 1 C 2 Cl 2, rt, 5 h % yield 89 p-c m-clc Au Au 2 1 Au 2 70% 39% ( 3 P)AuCl or (c-exc)aucl showed decreased reactivity!-ketoesters reacted but gave a complex reaction mixture alkene added by syringe pump Au 3 Li, C.-J. JACS 2004, 126, 6884 C C Bond Forming eactions Conia-Ene 5-exo-dig Cyclization 1% ( 3 P)AuTf CE, rt, 15 min 94% yield 1% [( 3 PAu) 3 ]BF 4 5% Tf same result; AgTf gave no reaction no precaution to exclude air or moisture necessary substrate time product yield n = C 2 C 2 n= h 18 h 16 h C 2 n 90% 90% a 88% C 2 8 h 83% 5 min C 2 99% a 5% catalyst used Toste, F.. JACS 2004, 126, 4526

8 C C Bond Forming eactions Conia-Ene 5-exo-dig Cyclization 8 = Et 50 min 95% (17:1) = 24 h 86% (4.2:1) 1 h 95% (4:1) Bn Bn n-pr 1 h 97% n-pr diastereoselectivity implies some degree of ordering in the transition state Toste, F.. JACS 2004, 126, 4526 Conia-Ene 5-exo-dig Cyclization chanistic Considerations LAu mech A 2 C A AuL 2 C Ac AuL 2 C Ac LAu mech B 2 C B AuL 2 C Ac AuL ( 3 P)AuTf (90%) ( 3 P)AuTf (48%) Toste, F.. JACS 2004, 126, 4526

9 C C Bond Forming eactions 5-endo-dig Carbocyclization 9 1% ( 3 P)AuTf C 2 Cl 2, rt = allyl, 90% (10 min) propargyl, 96% (5 min) C 2 C 2 I 1 h, 88% =, 83% (1 h), 74% (15 min), 94% (15 min) 90% n n= 1, 93% 2, 76% 2 C AuL LAu C 2 A B disfavorable A 1,3 strain Toste, F.. ACIE 2004, 43, 5350 C C Bond Forming eactions Enyne Cycloisomerization- Theoretical Predictions Z 6-endo-dig Z 5-exo-dig Z Z Z M n a Z M n b Z M n Z d M n c Z 1,2- shift M n FT calculations predict 5-exo-dig cyclization transition state 6 kcal/mol lower in energy catalyzed by (P 3 )Au for terminal alkynes (pathway B). Z c Z d Echavarren, A. M. ACIE 2004, 43, 2402

10 C C Bond Forming eactions Enyne Cycloisomerization- Experimental bservations 10 2 S 2 S 2% ( 3 P)AuCl 2% AgSbF 6 C 2 Cl 2, rt, 5 min 100% yield 2 S 2 S as solvent a t (min) yield product yield 2 C 2 C 2 C 2 C 25 91% 2 C 2 C 97% 2 C 2 C 2 C 2 C 10 96% (4:1 E:Z) 2 C 2 C 2 C 2 C 5 76% 2 C 2 C 48% Echavarren, A. M. ACIE 2004,43, 2402 Echavarren, A. M. JACS 2001, 123, a eaction run with 3% ( 3 P)AuC 3 with acid co-catalyst (BF 4 or 3 PW ). eaction times are 4 and 12 h. C C Bond Forming eactions Enyne Cycloisomerization Synthesis of 1,3- and 1,4-dienes TIPS 1% AuCl C 2 Cl 2, 30 min 93% yield 2 TIPS TIPS (1,4:1,3) n-c 3 7 n-c 3 7 TIPS TIPS 73% 82% (6:1) TIPS TIPS 99% (4:1) 99% (3:1) n-c 5 11 TIPS TIPS 88% 84% Kozmin, S. A. JACS 2004, 126, 11806

11 Proposed chanism for Enyne Cycloisomerization for the Synthesis of 1,3- and 1,4-dienes TIPS TIPS AuCl TIPS 2 1 TIPS AuCl TIPS 2 = AuCl TIPS 2 = AuCl TIPS AuCl 2 1 TIPS AuCl 2 1 AuCl TIPS 2 1 TIPS AuCl Kozmin, S. A. JACS 2004, 126, C C Bond Forming eactions Catalyst ptimization for Enyne Cycloisomerization C 2 Cl 2, rt 1% catalyst catalyst conversion (C)PdCl 2, 24 h ~ 4% PtCl 2, 24 h ~ 4% PtCl 2, AgBF 4, 24 h ~ 5% AgBF 4, 24 h trace ( 3 P)AuCl, AgBF 4, 5 min 100% ( 3 P)AuCl, 24 h 0%, 3 h 50% 5%, 15% AgTf gave complete conversion but substantial decomposition Toste, F.. JACS 2004, 126, 10858

12 C C Bond Forming eactions Substrates for Enyne Cycloisomerization 12 substrate catalyst product yield (d.r.) 1% ( 3 P)AuSbF 6 95% Br Br 1% ( 3 P)AuSbF 6 94% Bn n-pr 1% ( 3 P)AuSbF 6 Bn n-pr 98% (>99:1) Bn Et 1% ( 3 P)AuSbF 6 Bn Et 96% (97:3) TIPS TIPS 97% ee 98:2 d.r. 3% ( 3 P)AuPF 6 99% (>99:1) 91% ee Toste, F.. JACS 2004, 126, C C Bond Forming eactions Proposed chanistic ypothesis cis trans LAu cis trans AuL cis trans AuL cis trans LAu cis trans 1% ( 3 P)AuPF 6 99% yield n cat. ( 3 P)AuBF 4 n= 1, 72% n= 2, 66% n Toste, F.. JACS 2004, 126, 10858

13 C C Bond Forming eactions Cationic Au(I) Propargyl-Claisen earrangement 13 1% catalyst, C 2 Cl 2 10 min, rt; ab 4 n-bu n-bu 95% ee cat= ( 3 P)AuBF 4, 85% (4% ee) [( 3 PAu) 3 ]BF 4, 91% (90% ee) TIPS 1% [( 3 PAu) 3 ]BF 4 C 2 Cl 2, 50min, rt; ab 4, n-bu n-bu 95% ee 81% yield 94%ee, >20:1 d.r. specificity occur when pseudoaxial avoids A 1,2 interaction with vinyl Au 1 1 Au Au Toste, F.. JACS 2004, 126, C C Bond Forming eactions enol Synthesis 1 1 2% C, 20 C % yield C 2 65 Ts 97 Ts 94 Ts 93 C(C 2 ) 2 88 (Ts)C 2 81 Pd(II), Pt(II) work, but very slowly rxn not sensitive to 2 or 2 up to 5 equiv 18 2 gave < 1% 18 incorporation =, Ts.. Ts 4% C Ts Ts ashmi, A. JACS 2000, 122, ashmi, A. rg. Lett. 2001, 3, % 51%

14 14 A B G ML n ML n ML n C ML n L n M E F L n M L n M A Primary Kinetic Isotope Effect was not observed. ashmi, A. S. K. ACIE 2005, 44, 2798 I J MLn K MLn L C C Bond Forming eactions enol Synthesis Ts Ts 5% Cl Au Cl G Ts G and observable by M at -20 C intermediate can be enriched up to 80% utilizing pyridine complex calculations of G and predict they are similar in energy (< 1 kcal/mol difference) Ts ashmi, A. S. K. ACIE 2005, 44, ray Structure

15 C C Bond Forming eactions Arene Functionalization % 7% AgTf CE,! 1 Br t-bu 83 C, 87% (5% ) 50 C, 83% 50 C, 76% 83 C, 69% 2.5% 7% AgTf CE, 50 C, 3 h 82% yield typical Lewis acids do not work cyclization is stereospecific open epoxide at primary carbon, S 2-like e, C. JACS 2004, 126, 5964 trans only C C Bond Forming eactions Electron-rich Arene Functionalization Tf 5% 15% AgTf CE, 120 C 90% yield arene electrophile yield (linear) yield (branched) n-butf 70% < 5% n-butf 40% 50% n-butf 10% 80% n-butf 5% 90% e, C. JACS 2004, 126, 13596

16 C C Bond Forming eactions Electron-rich Arene Functionalization- chanistic Insight 16 ArAuCl 2 n-butf (2 eq) 2 eq AgTf Ar 70% linear product by 7 days (no branched observed) n-butf 20% 60% AgTf CE, 120 C, 1 h; sat'd acl n-bu ~ 65% ~ 12% ~ 20% 5% 15% AgTf CE, 120 C = Ms =, 90%, < 15% e, C. JACS 2004, 126, C C Bond Forming eactions Arene Addition to Electron-deficient Alkynes Ar C 2 2.5% 7% AgTf neat, 23 C Ar C 2 C 2 C 2 Et C 2 Et Br 99% 75% 97% 80% highly Z-selective (only olefin isomer detected) cationic LAu(I) works as well: M. eetz Eur. JC 2003, 3485 immediate color change when arene and cationic complex mixed 1 5% 15% AgTf CE, 50 C 1 1 =, 84%, 99%, 73% e, C. JC 2004, 69, 3669

17 C C Bond Forming eactions Labeling and Crossover Experiments 17 C 3 3 C C 3 C 2 Et 5% 15% AgTf CE, rt C 3 () 3 C C 2 Et C 3 88% 97% yield Crossover Experiment () 86% yield 52%- 5% 15% AgTf CE, rt () 99% yield 48%- e, C. JC 2004, 69, 3669 C Bond Forming eactions irected ydration of Alkynes 5% aaucl : 2 (9:1) reflux A B time (h) product % yield n-c 5 11 n-c A a 79 C 3 n-c A a 75 n-c 6 13 C 3 C 3 10 A 70 n-c B 91 a Product isolated as a single olefin isomer (E). 100 n-bu h 91% yield 0 2h 67% yield h 99% yield conditions: 3% aaucl 4 2 2, : 2 (10:1), ultrasound 90 1h 92% yield % yield Utimoto, K. Bull. Chem. Soc. Jpn. 1991, 64, 2013 Utimoto, K. Tet. Lett. 1897, 28,

18 C Bond Forming eactions irected ydration of Alkynes - chanistic ypothesis 18 5% aaucl : 2 (9:1) reflux A B Au III Au III A when 1 = Au III Au III tautomerize B Utimoto, K. Bull. Chem. Soc. Jpn. 1991, 64, 2013 C Bond Forming eactions ydration of Alkynes 1 2 2% aaucl 4-2 (10:1) reflux 1 2 A 1 2 B 1 2 time (h) product % yield n-c A 91 (C 2 ) 9 n-c A 91 C 3 5 A:B (40:60) 94 C A:B (57:43) % yield 1 2 2% aaucl 4, reflux 1 h 1 2 n-c n-c 6 11 n-c reproducible on gram scale reduced to Au(0) during reaction, preventing lower catalyst loadings Utimoto, K. J. rg. Chem. 1991, 56, 3729

19 C Bond Forming eactions Efficient ydration of Propyne 19 3 C (L)Au C 3 S 2, 40 C L initial TF (h -1) T 3 As 430 Et 3 P P () 3 P 610 > ~ P Au 3 C 3 P Au C 3 C 3 FT predicts more stable over E- isomer by ~ 2.4 kcal/mol 3 C 3 P C 3 Au 3 P C 3 Au at low conversion, Z:E! 8:1 end of reaction, Z:E! 2:1 two -80 C in C 2 Cl 2 (CM, Ms - ) add, one singlet add alkyne, one singlet calculations predict alkyne to bind cation over by ~ 6 kcal/mol secondary alcohols reacts ~ 10x slower Teles, J.. ACIE 1998, 37, 1415 C Bond Forming eactions Efficient ydration of Alkynes n-ex 0.01% ( 3 P)Au 50 mol% acid, additive - 2 (10:1) 1 h, 70 C n-ex acid additive % yield 2 S 4 2 S 4 35 C (1atm) 99 C 3 S PW w/o additional L, catalyst decomposition observed (particles) 2 S 4 conditions w/o added L C 3 n-pr n-pr 1% cat. 90% yield 0.2% cat 83% yield 0.2% cat 95% yield 42% yield 32% yield 0.2% cat. Tanaka, M. ACIE 2002, 41, 4563

20 C Bond Forming eactions Alcohol Addition onto Unactivated Terminal lefins 20 2% 3 PAuCl 2% AgTf, 85 C (4 eq) 84% yield Bn 15 1 =, 78% C 2, 68% 84% (5% cat) 1 BnC =, 71%, 80% (15:1) 75% (5% cat) 5.5:1 >95% yield 1% 3 PAuTf, 20 h, 85 C 75% conversion E:Z = 2.2:1 e, C. JACS 2005, 127, 6966 C Bond Forming eactions Intramolecular Trapping of Enyne Cycloisomerization Adduct with eteroatom ucleophile 5% C, 20 C 89% yield Ts Ts 89% yield ( 3 P)AuCl AgCl 4 82% yield 87% yield ( 3 P)AuCl AgCl 4 96% yield ( 3 P)AuCl AgCl 4 Kozmin, S. A. JACS 2005, 127, 6962

21 C Bond Forming eactions Intramolecular Trapping of Enyne Cycloisomerization Adduct with eteroatom ucleophile 21 10% C, 20 C 90% yield 10% C, 20 C 90% yield Kozmin, S. A. JACS 2005, 127, 6962 C Bond Forming eactions chanistic ationale or Kozmin, S. A. JACS 2005, 127, 6962

22 C Bond Forming eactions ydroamination of Alkynes % ( 3 P)Au % 3 PW neat, 70 C, 1-2 h % yield C 6 5 C BrC CC P Au P Au 2-C 4 3 S C A B n-c 3 7 C 3 4-BrC C 6 5 C internal alkynes less reactive (sterics?) reaction proceeds more smoothly if 1. amine is more electron withdrawing 2. alkyne is more electron donating Tanaka, M. rg. Lett. 2003, 5, 3349 Au(I) calculations predict B Attack by mode of A used to rationalize Au(III) amine additions (tetrahydropyridine synthesis) EW amine as a better reactant supports B Utimoto, K. eterocycles 1987, 25, 297 Utimoto, K. Synthesis 1991, 975 C Bond Forming eactions Indole Synthesis 2 4% aaucl Et or Et- 2 rt, 5 h 84% yield Au(III) salts gave best yields, AuCl (50%), PtCl 4 (20%), various Pd(II) and Cu(II) gave < 10%. t-bu 2 h, 83% 4 h, 80% S Cl Cl 20 h, 90% 2 Cl F 3 C 16 h, 66% 16 h, 60% Marinelli, F. Synthesis 2004, 4, 610

23 C, Bond Forming eactions Isoxazole Synthesis 23 5%, a 2 1 3, 2 50 C t (h) % yield 5 40 Bu 1 38 Bn 2 CC 2 C BzC 2 C Cl 3 Au 2 AuCl 2 Cl 1 Cl 3 Au Gasparrini, F. JACS 1993, 115, 4401 C Bond Forming eactions xazole Synthesis 5% C or C 2 Cl 2 rt t (h) % yield 12 >95 12 >95 20 > stereospecific addition of oxygen to activated alkyne 5% can be enriched up to 95% before isomerization to oxazole stable for weeks at -25 C * 2 C ashmi, A. S. K. L 2004, 6, 4391

24 C Bond Forming eactions Furan Synthesis 24 Et Et or Et Et 0.1% minutes, C quantitative Et Et 0.1% C, 1 h PMB 1% C 74% yield PMB 1% 61% yield C Ag(I) very slow reaction, PdCl 2 (C) 2 took about an hour ashmi, A. S. K. ACIE 2000, 39, 2285 C Bond Forming eactions Furan Synthesis 1 1% 1 u, C 2 Cl 2 rt, 1 h uc alkenynone u product alkenynone u product 1 = 62% 1 = 63% (1.2:1 d.r.) 1 = Larock,. JACS 2004, 126, % 90% Bn 63% Bn Bn 34% 40%

25 C Bond Forming eactions Furan Synthesis chanistic ationale 25 Cl 3 Au Michael Addition u A B u u u u 1% does not catalyze addition u to cyclohexenone or methylvinyl ketone under the specified conditions. Larock,. JACS 2004, 126, Assisted Bond Forming eactions Cyclopentanone Synthesis t-bu 2 2-5% ( 3 P)AuTf C, rt n-bu n-bu n-bu Ts 8 h, 80% 20 h, 85% 20 h, 81% 14 h, 45% 10 h, 48% conditions: 5% ( 3 P)AuSbF 6 C, -20 C % yield SM % ee Product % ee Toste, F.. JACS 2005, 127, 5802

26 -Assisted Bond Forming eactions Cyclopentanone Synthesis t-bu Piv LAu 3 Piv 3 LAu 3 t-bu 2 AuL 3 isolated Cp intermediate mixture of E:Z olefins gives selective reaction of E isomer only (recover Z) AuL 2 3 t-bu Toste, F.. JACS 2005, 127, Assisted Bond Forming eactions apthylketone Synthesis % CE, 80 C 2-6 h A B A:B ratio % yield n-c : :<1 96 Si 3 16:84 82 CC 3 <1:99 75 Si 3 99:<1 92 when 3 = M evidence for substitution patter n-c :8 91 other solvents work (EtAc, dioxane, C) no reaction w/o Yamamoto, Y. JACS 2002, 124, 12650

27 -Assisted Bond Forming eactions apthylketone chanistic ypothesis A Cl 3 Au step-wise intermediate possible Yamamoto, Y. JACS 2002, 124, Assisted Bond Forming eactions apthylketone chanistic ypothesis 3% CE, 80 C =, 40%, 60% 3% C, 80 C, 3 h 57% yield 3%, 2 C, 80 C, 3 h 61% yield Yamamoto, Y. JACS 2002, 124, yker, G. ACIE 2003, 42, 4399

Homogeneous Gold Catalysis - Unique Reactivity for Activation of C C Multiple Bonds

Homogeneous Gold Catalysis - Unique Reactivity for Activation of C C Multiple Bonds 1 rganic Seminar 2011.05.09 omogeneous Gold Catalysis - Unique Reactivity for Activation of C C Multiple Bonds ysical rganic Chemistry Laboratory (Nakamura Laboratory) D2 Masaki Sekine Development of Gold