SLIDE 1
RACEMIZATION OF CHIRAL sec-ALCOHOLS WITH BIFUNCTIONAL CATALYSTS - - PowerPoint PPT Presentation
RACEMIZATION OF CHIRAL sec-ALCOHOLS WITH BIFUNCTIONAL CATALYSTS - - PowerPoint PPT Presentation
RACEMIZATION OF CHIRAL sec-ALCOHOLS WITH BIFUNCTIONAL CATALYSTS OH O * R R' R R' X X X Ru H Ru H Ru N N N KO t- C 4 H 9 Cl H H O H OH H R R' R R' arene ligand Ru Ru X Ru Me 2 N O Cl Cl H TsN Ru Cl H NH
SLIDE 2
SLIDE 3
A POSSIBLE MECHANISM OF RACEMIZATION BY Ru –AMINE COMPLEXES
KOt-C4H9 Ru X NH Ru X NH2 Cl Ru X HN H H HN Ru X H H O R' R
- r
diastereomeric R R' O R R' OH R R' OH NH Ru X H H O R' R HN Ru X H H O R R' R R' O HN Ru X H H O R R' + R R' OH +
SLIDE 4
EFFECTIVE CHELATE AMINE LIGAND FOR Ru
KOt-C4H9 toluene, 30 °C OH OH [RuCl2(hmb)]2 amine ligand HS NH2 HO NH2 TsN NH2 H amine ligand ON chelate ee, % 7 14 76 HO NH2 HO S NH2 HO NH2 O O O 58 86 >99 HO NH2 O NH2 H 88 86 HS NH2 HS NH2 >99 >99 TsN NH2 >99 amine ligand SN chelate ee, %
- ther amine ligand
>99% ee PhS NH2 91 HS NMe2 99 H 24 h S/C = 100 postulated catalyst M X NH
SLIDE 5
LIGAND EFFECT: ARENE LIGANDS
KOt-C4H9 toluene, 30 °C OH OH [RuCl2(arene)]2 99 99 7 >99% ee 24 h S/C = 100 92 68 arene ligand ee, % arene ligand ee, % Cl Ru Ru Cl Cl Cl [RuCl2(arene)]2 Rn Rn HS(CH2)2NH2 94
SLIDE 6
EFFECTIVE CHELATE AMINE LIGAND FOR Rh or Ir
KOt-C4H9 toluene, 30 °C OH OH [Cp*MCl2]2 amine ligand HS NH2 HO NH2 TsN NH2 H amine >99% ee 24 h S/C = 100 Metal Ir Rh 97 >99 >99% ee 99 98 >99 postulated catalyst M X NH none 97 99
SLIDE 7
SYNTHESIS OF PREFORMED CATALYST PRECURSORS
[RuCl2(hmb)]2 Ru S NH2 S HS NH2 NH2
P-1 (#2) R1 = 0.120 wR2 = 0.318
2-propanol KOH (excess) THF CH3ONa
R1 = 0.079 wR2 = 0.188 P-1 (#2)
78% yield 68% yield Ru Ru N H S H Cl 2-propanol 91% yield S Ru Ru S H2N NH3 Cl Cl2 1/2
R1 = 0.057 wR2 = 0.148 P-1 (#2)
(Ru:SN=2:5) KOt-C4H9
SLIDE 8
PREPARATION OF GROUP IX SN COMPLEXES
HS NH2 S Ir Ir S H2N NH3 Cl Cl2 [Cp*IrCl2]2 + KOt-C4H9 2-propanol 2
1H NMR (δ, CDCl3): 1.60 (s, 15H, Cp*)
1.80 (s, 15H, Cp*) ESI-MS: m/z 841 [M-H]+ HS NH2 S Rh Rh S H2N NH3 Cl Cl2 [Cp*RhCl2]2 + KOt-C4H9 2-propanol 2
1H NMR (δ, CDCl3):1.61 (s, 15H, Cp*)
1.80 (s, 15H, Cp*) ESI-MS: m/z 663 [M-H]+
SLIDE 9
CATALYTIC ACTIVITY OF ISOLABLE RuSN COMPLEXES
KOt-C4H9 toluene, 30 °C OH OH Ru cat Ru S NH2 S NH2 >99% ee 6 h Ru Ru N H S H Cl S/C = 100 S Ru Ru S H2N NH3 Cl Cl2 6% ee Ru cat: 99% ee 99% ee
SLIDE 10
RACEMIZATION WITH PREFORMED Ru, Rh, Ir COMPLEXES
KOt-C4H9 toluene, 30 °C OH OH metal cat >99% ee 24 h S/C = 100 S Rh Rh S H2N NH3 Cl Cl2 S Ru Ru S H2N NH3 Cl Cl2 [Cp*RhCl2]2 [RuCl2(hmb)]2 NH2 HS NH2 HS + + 99 6% ee >99 36 metal cat : (3 eq) S Ir Ir S H2N NH3 Cl Cl2 [Cp*IrCl2]2 NH2 HS + 64 98
SLIDE 11
S Ru Ru S NH2 H2N Cl2
A POSSIBLE ROUTE FOR GENERATION OF ACTIVE CATALYSTS
base 16e 18e Ru S NH S Ru Ru S NH HN S Ru Ru S H2N NH3 Cl Cl2 Ru S NH2 H R1 R2 OH R1 R2 OH R1 R2 O R1 R2 O base
SLIDE 12
SYMMETRIC DIMER
[RuCl2(hmb)]2 + HS NH2 S Ru Ru S NH2 H2N Cl2 18% yield
R1 = 0.060 wR2 = 0.176 P21/n (#14) δ 1.78 (s, 36H)
1H NMR (CD3OD) :
2
Bond lengths (Å) Bond angles (°) Ru(1) –S(1) 2.411 S(1) –Ru(1) –N(1) 78.00 S(1) –Ru(1) –S(2) 82.38 Ru(1) –S(2) 2.418 Ru(1) –N(1) 2.183 S(2) –Ru(1) –N(1) 80.30 δ 7.19 (t, 2H) δ 7.32 (t, 2H) δ 6.48 (m, 4H)
CH2Cl2 50 °C
SLIDE 13
TRANSFER HYDROGENATION
KOt-C4H9 30 °C O OH metal cat 1 h S Ir Ir S H2N NH3 Cl Cl2 S Rh Rh S H2N NH3 Cl Cl2 [Cp*IrCl2]2 [Cp*RhCl2]2 NH2 HS NH2 HS + + 84 33 71 51 metal cat: (3 eq) OH O + + [ketone] = 1.0 M in 2-propanol S Ru Ru S H2N NH3 Cl Cl2 [RuCl2(hmb)]2 NH2 HS + 83% 36
SLIDE 14