rganometallic Study Meeting Chapter 17. Catalytic Carbonylation 17.1 verview C or 3 3 C 3 C C 3 horrcat. Ar-X or alkene ' d cat. 2011/10/6 K.isaki or ' or N n 2 1 alkene, 2 Coorhcat. d cat. alkene C carbon monooxide epoxide/aziridine Co cat. Co,Mo,h u,r, Ticat. alkene alkyne X 17.2. Carbonylation to roduce Acetic Acid 17.2.1. h-catalyzed carbonylation of Me to produce Ac(Monsanto rocess) C 3 + h () 2 2 30-40atm,180 o C 3 C commercialized in 1970 3 C C 3 non-metallic cycle 2 C 3 3 C rate-determining step C 3 h oxidative insertion addition(s N 2) h rganometallic Cycle detected by ( =2055,1985cm -1 ) reductive elimination C 3 h kinetically unstable intheabsenseof dimer (X-ray) C 3 h 0 th order microreversibilitywasconfirmedbyoxidativeadditionofactoh() 2 2 C 3 C 3 h h + h 3 C
17.2.2.h-catalyzedcarbonylationofMeActoproduceAc 2 (Eastmanrocess) 3 C h () 2 2,i C 3 + anhydrous conditions 3 C C 3 commercializedin1983 3 C C 3 * works similarly instead of i. C 3 i i-cyclie iac h 3 C Same cat cycle as Monsanto rocess 3 C C 3 17.2.3. r-catalyzed carbonylation of Me to produce Ac(Cativa rocess) C 3 + r() 2 2 [u() 3 2 ] 2 (promoter) 3 C established in 1990s #5timesmoreactive #more 2 tolerant # more soluble catalyst # less expensive metal than h detected by ( =2100,2047cm -1 ) Me C 3 3 C r Ac oxidative addition reductive elimination C 3 r fast (r>150xh) C 3 r theratedependson[],[ 2 ],[MeAc],[Me],[upromoter],[r] (nonlinear) (h system only depends on[h] and [Me]) insertion rate-determining step (h>10 5 xr) role of promoter = iodide acceptor C 3 r C 3 r neutral slow 1/2[u() 3 2 ] 2 u() 3 3 fast x~20 + C C 3 r C 3 r
17.3. ydroformylation 17.3.1. verview 17.3.2.Co() 4 catalysis(xoprocess) Co() 4 + / + 2 (1/1) 120-170 o C 200-300 atm branched(b) linear(l) 2 Co 2 () 8 C Co C Co d 8,18e d 8,16e Co product 2 d 6,18e C C Co d 8,18e reversible& isomerizable rate-determining step (ratedependency=[ 2 ][] -1 ) C C Co d 8,18e C Co d 8,16e C Co C d 8,18e C Co d 8,16e #highpressureofisrequiredtosuppresscatdecomp(formationofcoclusterormetallicco) # all reactions have the potential to be reversible #l/bratio=3~4:1atbest 17.3.3.Co() 3 ( 3 )catalysis stable, high MW phosphine (industrially fabored) ( 3 = n Bu 3 ) C=C isomerization is very fast.
17.3.4. h catalysis h() 2 (acac) h 3 + / 2 (1/1) 70-120 o C 10-50 atm + commercialized in 1970s lowerpressure improved l/b less byproduct lab-scale application <reactivity> ' ' '' ' h() 2 (acac) / 2 h 3 product h 3 h h 3 geometrical isomer isobservedbynm 2 h 3 h h 3 rate-determining step (rate [ 2 ] 0 [alkene][h][ 3 ] -1 [] -1 ) h 3 h h 3 h 3 C h h 3 h 3 h h 3 h 3 C h h 3 h 3 h h 3
<hosphine Effect> empirical: wider B.A. gives better l/b ratio M natural bite angle = MM caluculated h ap-eq cat. biteangle<90 o h eq-eq cat. biteangle>90 o C 4 9 h 2 h 2 h h() 2 (BSB)(4mM) / 2 (6atm),34 o C BA=113 o eq-eq coordination is confirmed by X-ray and NM. + C 4 9 C 4 9 l/b=66.5 (cf.l/b=2.1/fordppe(ba=85 o )) irreversible alkene insertion originated high selectivity. empirical: eq:more EWG ap:more EDG C h ' faster reaction high l/b selectivity ietw.n.m.vaneeuwenetal.jacs1998,120,11616. S Ar 2 = [eq-eq]-[ap-eq] [eq-eq]+[ap-eq] ofh() 2 () Ar 2 thi-xantphos (Ar) similar B.A. bite angle does not always correlate. most important effect of using electron-poor ligand is to facilitate dessociation conditions: / 2 =1,(/ 2 )=20bar,ligand/h=5 substrate/h=637,[h]=1.00mm C h ' destablize +alkene faster C h '
<hosphile igand> #highl/bratio # faster reaction # suppressed side reaction (hydrogenation) thanar 3 <Scope> internal alkene acetal w/ directing group <Enantioselective reaction> challenges branched product should be selectively formed. simple alkene's directing nature is small. racemization must be suppressed. chiral phosphine is far from reaction space. olefin with EWG gives branched product. scope with h-bnas successful ligand families Babin& W hiteker van eeuwen& Claver Nozaki& Takaya andis
17.4. ydroaminomethylation / 2 h cat. 2 N 2 cat. N 2 <Scope> usually linear major. same above biphasic system targeting fine chemicals challenges # prevent catalyst deactivation with excess amines # e-rich cat enough to reduce e-rich enamine not to prevent hydroformylation
17.5. ydrocarboxylation/ ydroesterification d/ cat. acid co-cat. + ' or ' ' example =alkyl =aryl Me naproxen <Scope> 12,000 TN/hr (ligand = DTBMB) intramolecular rxn high FG tolerance alkyne 50,000TN/hr@60 o C =2-(6-Me-y)h 2 depends on the ligand nature. Me d Me Me d Me alkoxide cycle Me hydride cycle d Me d Me d d copolymer copolymer (more probable in d/dtbmb)
17.6. Carbonylation of Epoxides/ Aziridines <Scope> Alper's system X + (X=orN') Co() 4 cat. X acid co-cat. Coates'system(5=[Cr (Et 8 -porphyrinato)(thf) 2 ][Co() 4 ]) (N = bis(triphenylphosphine)iminium) double carbonylation aziridines ring-opening carbonylation addition of ewis acid acclerate the rxn. Co 2 () 8 +u 3 () 12 system Co 2 () 8 +1,10-hen+BnBrsystem w/o 2
17.7. Carbonylation of rganic alides(carbonylative Cross Coupling) X + +Nu (Nu=',' 2 N,'-M) d cat. Nu scope is similar to that of cross coupling. =alkylisremainstobedeveloped. <Scope> review: Nicolaou, K. C. et al. ACE 2005, 44, 4442. detailsdependon-xandnu.
17.8. Copolymerization of and lefins + d cat. n similar conditioins of hyroesterification in the absence of acid co-catalyst weakly nucleophilic alcohol or aprotic solvent is preferred. + ethylene resting state athigh d d =polymer d bidentate ligand(dppp) is favored. rigin of perfect alteration [d]=d(dppp) + d resting state atlow rate-determining step Catalyst decomposition or generation of d(0) metal from d hydride unfavorable insertion into M-acyl bond is thermodynamically unfavorable. Chain Termination presence of absence of still active cat. still active cat. still active cat.
+ -olefin chiral Box + d cat. depends on ligand and reaction conditions bipy 1,10-phen +styrene very high regioselectivity + aliphatic olefin d-bnas cat. 4 : 1 d-bnas cat. reversed regiochemistry compered to styrene, but usually not high degree isotactic copolymer ketal is final product.
17.9. auson-khand eactions(k) metal reagent or catalyst + + discovered in eary 1970s typical conditions: stoichiometricco 2 () 8 additive effect (also see isaki's handout, chapter 5) M() x 3 N- 3 N () x-1 M M() x-1 (N 3 ) + 2 effective only to intramolecular K catalytic conditions Cp 2 Ti() 2,u x () y,[h() 2 Cl] 2,Fe,d, r(cod)cl(h 3 ),Mo(dmf) 3 () 3,W() 5 (thf) also showed catalytic activity. *Co 2 () 8 isthermallyunstable Catalytic asymmetric K is also active. ntermolecular K : difficult to control the regioselectivity Kraftetal. chelating auxiliary is the choice. Yoshida&tamietal.
Application in Total Synthesis Jamison& Schreiber et al.: synthesis of(+)-epoxydictymene Nicholas rxn K Magnus,.etal.T1985,26,4851. totally irreversibe in the presence of slow