Stable gold(iii) catalysts by oxidative addition of a carboncarbon

Transcription

1 Stable gold(iii) catalysts by oxidative addition of a carboncarbon bond Chung-Yeh Wu, Takahiro oribe, Christian Borch Jacobsen & F. Dean Toste ature, 517, (2015) presented by Ian Crouch Literature Seminar Burke Group

2 Finding ew eactivity in igh-valent Transition Metals Low-valent, late transition metal catalysis: Pd 0, i 0, h 1, etc. -indispensible for chemical synthesis -widely used for bond formation (C-C, C-, C-) i (IV) catalyzed C-heteroatom bond formation: Science Express, February 5, 2015, /science.aaa4526 Pd (IV) catalysis review: Angew. Chem. Int. Ed. 2009, 48, C-halogen bond formation: Science, 2011, 334, Gold(I) catalysis reviews: Chem. ev. 2011, 111, Chem. ev. 2011, 111,

3 Finding ew eactivity in igh-valent Transition Metals Low-valent, late transition metal catalysis: Pd 0, i 0, h 1, etc. -indispensible for chemical synthesis -widely used for bond formation (C-C, C-, C-) oxidation igh-valent, late transition metal catalysis: Pd II /Pd IV, i IV -C- activation -C-halogen bond formation -C-heteroatom bond formation i (IV) catalyzed C-heteroatom bond formation: Science Express, February 5, 2015, /science.aaa4526 Pd (IV) catalysis review: Angew. Chem. Int. Ed. 2009, 48, C-halogen bond formation: Science, 2011, 334, Gold(I) catalysis reviews: Chem. ev. 2011, 111, Chem. ev. 2011, 111,

4 Finding ew eactivity in igh-valent Transition Metals Low-valent, late transition metal catalysis: Pd 0, i 0, h 1, etc. -indispensible for chemical synthesis -widely used for bond formation (C-C, C-, C-) oxidation igh-valent, late transition metal catalysis: Pd II /Pd IV, i IV -C- activation -C-halogen bond formation -C-heteroatom bond formation Gold(I) catalysis: -soft, carbophilic Lewis Acid -C-C, C-, and C- bond formation i (IV) catalyzed C-heteroatom bond formation: Science Express, February 5, 2015, /science.aaa4526 Pd (IV) catalysis review: Angew. Chem. Int. Ed. 2009, 48, C-halogen bond formation: Science, 2011, 334, Gold(I) catalysis reviews: Chem. ev. 2011, 111, Chem. ev. 2011, 111,

5 Finding ew eactivity in igh-valent Transition Metals Low-valent, late transition metal catalysis: Pd 0, i 0, h 1, etc. -indispensible for chemical synthesis -widely used for bond formation (C-C, C-, C-) oxidation igh-valent, late transition metal catalysis: Pd II /Pd IV, i IV -C- activation -C-halogen bond formation -C-heteroatom bond formation Gold(I) catalysis: -soft, carbophilic Lewis Acid -C-C, C-, and C- bond formation oxidation Gold(III) catalysis: -hard, oxophilic Lewis Acid -novel reactivity in C-C and C-heteroatom bond formation i (IV) catalyzed C-heteroatom bond formation: Science Express, February 5, 2015, /science.aaa4526 Pd (IV) catalysis review: Angew. Chem. Int. Ed. 2009, 48, C-halogen bond formation: Science, 2011, 334, Gold(I) catalysis reviews: Chem. ev. 2011, 111, Chem. ev. 2011, 111,

6 The eactivity of Gold (I) and Gold (III) 3 P Au I 6s mostly empty 6s valence orbital linear, bi-coodinate geometry Au 5d orbitals are low energy due to decreased electron/electron repulsion because of relativistic contraction of other orbitals. 2 1 P 3 X - Au I 1 2 Au I Ar X Ar Au III X oxidative addition/reductive elimination disfavored relative to other late transition metals and not commonly encountered elativistic Effects in omogeneous Gold Catalysis, ature. 2007, 446,

7 The eactivity of Gold (I) and Gold (III) 3 P Au I 6s mostly empty 6s valence orbital linear, bi-coodinate geometry Au 5d orbitals are low energy due to decreased electron/electron repulsion because of relativistic contraction of other orbitals. 2 1 P 3 X - Au I 1 2 Au I Ar X Ar Au III X oxidative addition/reductive elimination disfavored relative to other late transition metals and not commonly encountered n the observed alkynophilicity of gold (I) catalysts: Au Complex 1 is 10 kcal/mol more stable than 2, but alkynes have lower Ms and LUMs than the corresponding alkene and therefore are more electrophilic and less nucleophilic. 1 2 Au elativistic Effects in omogeneous Gold Catalysis, ature. 2007, 446,

8 The eactivity of Gold (I) and Gold (III) 3 P Au I 6s mostly empty 6s valence orbital linear, bi-coodinate geometry Au 5d orbitals are low energy due to decreased electron/electron repulsion because of relativistic contraction of other orbitals. 2 1 P 3 X - Au I 1 2 Au I Ar X Ar Au III X oxidative addition/reductive elimination disfavored relative to other late transition metals and not commonly encountered n the observed alkynophilicity of gold (I) catalysts: Au Complex 1 is 10 kcal/mol more stable than 2, but alkynes have lower Ms and LUMs than the corresponding alkene and therefore are more electrophilic and less nucleophilic. 1 2 Au 1 2 C Au 2 1 mol % [Au(P 3 )]Tf C 2 C 3 elativistic Effects in omogeneous Gold Catalysis, ature. 2007, 446, Angew. Chem. Int. Ed. 2009, 48, 2-14.

9 The eactivity of Gold (I) and Gold (III) Gold(III) catalysis mainly limited to inorganic salts: Cl Cl Cl Au Au Cl Cl Cl Br Br Br Au Au Br Br Br Au lingandless, not tunable high redox potential cat. AuCl 3 MeC Eur. J. rg. Chem. 2006, low yield oxidative coupling products Au I

10 The eactivity of Gold (I) and Gold (III) Gold(III) catalysis mainly limited to inorganic salts: Cl Cl Cl Au Au Cl Cl Cl Br Br Br Au Au Br Br Br Au lingandless, not tunable high redox potential cat. AuCl 3 MeC Eur. J. rg. Chem. 2006, low yield oxidative coupling products Au I Gold(III) halide complexes have lacked either catalytic activity or stability. SbF 6 - AgSbF 6 - AgCl Cl Au Cl Cl Au Cl Cl catalytically inactive rganometallics. 2007, 26, rganometallics. 2010, 29, unstable to reduction

11 Accessing a Stable Gold (III) Catalyst a M n Typically halogen-based oxidation M n2 Low-valent catalysis Strong oxidants: X 2, F, CF 3, XS, IX 2, XeF 2, X, and so on igh-valent catalysis b X C [] L Au (I) Transmetallation X L Au (III) X L Au (III) C [g] or [Sn] X X Poor catalyst/unreactive ew strategy: carbon carbon bond cleavage C C More sterically encumbered and greater stability, even in active cationic form ature, 517, (2015)

12 Accessing a Stable Gold (III) Catalyst Bu 2 Sn Au Cl 1 ICl 2 IPrAuCl 3 2 with or without Ag Au Cl 3 8 yield from 1 AgSbF 6 DCM, T -AgCl = or Me Au 2 SbF - 6 Cl - AgSbF - 6 = or Me eq DMF = Au SbF 6 - SbF 6 - Au 4 6 ature, 517, (2015)

13 ATICLE Cationic Au III L in Mukaiyama-Michael eactions a 8 TMS i Pr Me 2 /toluene T,18 h 1 (10 mol%) AgTf (10 mol%) AgTf (10 mol%) i Pr 1,2-adduct 1,4-adduct i Pr = 38% yield <2:98 10a, = 76% yield >98:2 10b, = n Pr 1,4/1.2 adduct 86% yield >98:2 b TBS 9 Me 2 /toluene T,18 h 1 (10 mol%) AgTf (10 mol%) AgTf (10 mol%) 1,2-adduct 2 1,4-adduct 2 = yield* 11a, = 78% yield >98:2 d.r. 66:33 11b, = n Pr 69% yield* >98:2 d.r. 72:28 ature, 517, (2015)

14 The eactivity of Bulky Lewis or Bronstead Acids i-pr i-pr i-pr i-pr S9 P i-pr P i-pr 3% S9 or 1 S10, DCM, T, 20h. Aldehyde eagent Catalyst Conversion Product S9 o conv. - S9 o conv. - S9 o conv. - S9 o conv. - S9 ~1 S10 ~35% S10 Full conv. Ti(i-Pr) 2 S10 o conv. - S10 o conv. - S10 S10 ~2 Conversion was determined in the crude mixture as compared to the amount of aldehyde ature, 517, (2015)

15 Me 2 /toluene In-Situ xidative Addition to Au III T,18 h Mukaiyama-Michael after in-situ oxidative addition: c IPrAuCl 1 (10 mol%) AgX (10 mol%) 30 mol% IPrAu(III)( 4 -biphenyl)x 5 =, X = SbF 6 2 Catalyst (10 mol%) Yield 12 = Me, X = Tf IPrAuSbF 6 Br 2 IPrAuSbF 6 ICl 2 TMS i Pr in situ generated 12 (10 mol%) Me 2 /toluene T,18 h ipr 10a 72% yield 1,4-/1,2-adduct = >98:2 IPrAuSbF 6 XeF 2 (8% 1,2-adduct) d 1 (10 mol%) AgSbF 6 (10 mol%) i Pr (8 equiv.) TMS 13 CD 2 Cl 2, T, 90 min Biphenylene (40 mol%) i Pr AgSbF 6 (10 mol%) equiv. C 2 Cl 2, 30 min C 2 Cl 2 /Me 2 y for 1,4 e 3 Examples of selective Au(III)-catalysed 1,4-additions. kaiyama Michael addition. Tf, trifluoromethanesulfonate. b, itronate ael-addition. d.r., diastereomeric ratio; TBS, tert-butyl dimethyl silyl. c, In situ generation of IPrAu(III)(Me 4 -biphenyl) catalyst for Mukaiyama2Michael addition. d, ne-pot tandem Au(I)/Au(III)- and Au(III)/Au(III)-catalysed reactions. *The yield is determined by M. ature, 517, (2015)

16 Me 2 /toluene In-Situ xidative Addition to Au III T,18 h Mukaiyama-Michael after in-situ oxidative addition: c IPrAuCl 1 (10 mol%) AgX (10 mol%) 30 mol% IPrAu(III)( 4 -biphenyl)x 5 =, X = SbF = Me, X = Tf Catalyst (10 mol%) IPrAuSbF 6 Br 2 Yield TMS i Pr in situ generated 12 (10 mol%) Me 2 /toluene T,18 h ipr 10a 72% yield 1,4-/1,2-adduct = >98:2 IPrAuSbF 6 ICl 2 IPrAuSbF 6 XeF 2 (8% 1,2-adduct) Tandem Au I /Au III catalysis: d equiv. 1 (10 mol%) AgSbF 6 (10 mol%) i Pr (8 equiv.) 10 CD mol 2 Cl % 2, IPrAuCl T, 90 min 10 mol % AgSbF 6 8 eq IPA, DCM T, 90 min. AgSbF 6 (10 mol%) C 2 Cl 2, 30 min e 3 Examples of selective Au(III)-catalysed 10 mol % IPrAu(biphenyl)Cl 1,4-additions. 10 mol % AgSbF kaiyama Michael addition. Tf, trifluoromethanesulfonate. 6 b, itronate ael-addition. d.r., diastereomeric ratio; TBS, tert-butyl dimethyl silyl. 8 eq IPA, DCM T, 90 min. ature, 517, (2015) then Biphenylene 40 (40 mol mol%) % TMS i-pr C 2 Cl 2 /Me 2 i-pr 2 C TMS i Pr 57% yield >98% selectivity for 1,4 y for 1,4 c, In situ generation Me of IPrAu(III)(Me 4 -biphenyl) catalyst for 2, DCM i-pr 2 C Mukaiyama2Michael 4Å mol. sieves addition. d, ne-pot tandem Au(I)/Au(III)- and Au(III)/Au(III)-catalysed reactions. *The yield is determined by M. TMS i-pr 53% yield >98% selectivity for 1,4

17 Δ-Selective eactions With Dienals δ-selective thiol addition: ATICLE ESEAC Et 16b S 2 equiv. 3 (20 mol%) TBP AgSbF 6 (10 mol%) C 2 Cl 2 /Me 2, T Et S 17, 64% yield >98:2 for δ-selectivity d.r. 52:48 Catalyst (20 mol%) IPrAu(I)SbF 6 Yield for 16a -/, -/ -selectivity 16b: = Et 16c: = >95:2.5:2.5 >95:2.5:2.5 84:10:6 16a AgTf 2 (10 mol%) Me 2 /toluene T, 18 h 19a 85% yield, -/, -selectivity = >98:2 endo:exo = 88:12 Catalyst (10 mol%) IPrAu(I)Tf 2 AgTf 2 X Ar Ar TMS Yield <2% ature, 517, (2015) Ar = 3,5-CF 3 -C 6 3 X = 2-nitrobenzoic acid

18 Δ-Selective eactions With Dienals δ-selective thiol addition: ATICLE ESEAC a b Et Et 16b δ-selective 16breduction: 16b: = Et 16c: = S S 2 equiv. 3 (20 mol%) 2 equiv. TBP TBP 3 (20 mol%) AgSbF 6 (20 mol%), C 2 Cl 2, T AgSbF 6 (10 mol%) C 2 Cl 2 /Me 2, T AgSbF 6 (10 mol%) C 2 Cl 2 /Me 2, T -/, -/ -selectivity >95:2.5:2.5 >95:2.5:2.5 84:10:6 Et 2 C 3 (10 Cmol%) 2 Et 16 AgTf 2 (10 mol%) 18 Me 2 /toluene -/, -/ -selectivity 16a: = Me 18a: 65% yield* >95:2.5:2.5 16a T, 18 h 19a 16b: = Et 18b: 86% yield* >95:2.5:2.5 16c: = 18c: 76% yield 84:10:6 85% yield, -/, -selectivity = >98:2 endo:exo = 88:12 AgTf 2 (10 mol%) ature, 517, (2015) Me 2 /toluene Et S Catalyst (20 mol%) S IPrAu(I)SbF 6 Ar TMS Ar X Catalyst (10 mol%) 17, 64% yield >98:2 for δ-selectivity d.r. 52:48 Et Catalyst (20 mol%) Catalyst IPrAu(I)SbF (10 mol%) 6 IPrAu(I)Tf 2 AgTf 2 Yield for 16a 17, 64% yield >98:2 for δ-selectivity d.r. 52:48 Yield Yield for 16a <2% Yield IPrAu(I)Tf Ar = 3,5-CF 3 -C X = 2-nitrobenzoic acid AgTf ATICLE ESEAC

19 Catalyst (20 mol%) Δ-Selective eactions With Dienals IPrAu(I)SbF 6 Yield for 16a γ,δ-selective Diels-Alder: 16b: = Et 16c: = -/, -/ -selectivity >95:2.5:2.5 >95:2.5:2.5 84:10:6 16a AgTf 2 (10 mol%) Me 2 /toluene T, 18 h 19a 85% yield, -/, -selectivity = >98:2 endo:exo = 88:12 Catalyst (10 mol%) IPrAu(I)Tf 2 AgTf 2 X Ar Ar TMS Yield <2% in situ generated 5 (10 mol%) Me 2 /toluene 19 T, 24 h, -/, -selectivity = >98:2 Ar = 3,5-CF 3 -C 6 3 X = 2-nitrobenzoic acid 16a: = Me 16b: = Et 16b: = Et (15 mol% biphenylene was used) 16d: = C 2 C(C 3 ) 2 16e: = (C 2 ) 2 CC 2 16f: = (C 2 ) 2 19a: 19b: 19d: 19e: 19f: Yield 74% 92% 59% 62% 61% endo:exo 86:14 80:20 19b: 88% 80:20 69:31 79:21 82:18 mote selectivity in Au(III)-catalysed additions to dienals. a, d-selective thiol addition and reduction reactions. Et, ethyl; cat, catalyst. b, c, d-selective reaction and in situ generation of the IPrAu(III)(biphenyl) catalyst for Diels2Alder reactions. ature, 517, (2015)

20 added cis-unsaturated aldehyde-allene 20 ( mmol, 8.2 mg) in C 2 Cl 2 (125 µl). The Au III mixture was left to stir for 24 h at room temperature and then analyzed by -Catalyzed [22] Cycloaddition of 1 M. an Allene-Aldehyde Entry3: The solution of cis-unsaturated aldehyde-allene 20 ( mmol, 8.2 mg) in C 2 Cl 2 (125 µl) was left to stir for 24 h under irradiated condition using a 450 W anovia g-vapor lamp and then analyzed by 1 M. Me 2 C Me 2 C 20 Entry4, 5: To a vial equipped with a stirring bar was added organocatalyst ( mmol) AgSbF 6 (10 mol%) C 2 Cl 2, T, 24 h Me 2 C Me 2 C and the desired solvent (125 µl). To this mixture was added cis-unsaturated aldehyde-allene 20 ( mmol, 8.2 mg). The mixture was left to stir for 24 h at room temperature and then analyzed by 1 M. 21, 7 yield cis:trans = 89:11 Table S4. Intramolecular [2 2] cyclization of cis-unsaturated aldehyde-allene by Figure 5 Au(III)-catalysed [2 1 2] cycloaddition of an allene-aldehyde. different catalysts 22 JAUAY 2015 V 2015 Macmillan Publishers Limited. All rights reserved Entry catalyst solvent emark 1 IPrAuCl AgSbF 6 C 2 Cl 2 2 MeAlCl 2 C 2 Cl 2 3 none (hυ) C 2 Cl 2 4 S3 C 2 Cl 2 5 S3 Me: 2 (95:5) o product formed. o product formed. (E)-Unsaturated aldehyde was obtained o product formed. Aldehyde degradation. o product formed. (E)-Unsaturated aldehyde was obtained o product formed. Unknown product was obtained (ca. 50 %). ature, 517, (2015)

21 A Model for bserved Selectivity The X-ray structure of IPrAu(III)(biphenyl)(η 1 -cinnemaldehyde)][sbf 6 ]: i Pr i Pr i Pr i Pr SbF 6 Au 22 C C C Implications and future directions: enantioselective variants reaching stable high-valent transition metals using biphenylene catalyst development with the goal of efficient access to complex structures ature, 517, (2015)