RACEMIZATION OF SECONDARY ALCOHOL OH OH Ru cat. R R Ru cat: - - PowerPoint PPT Presentation

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Feb 21, 2023 521 likes •644 views

RACEMIZATION OF SECONDARY ALCOHOL OH OH Ru cat. R R Ru cat: O H O Ph Ph Ph Ph H + 5KOH Ph Ph Ru Ru P(C 6 H 5 ) 3 Ru Ph Ph Cl P(C 6 H 5 ) 3 OC CO CO OC Shovo (1986) Bckvall (1999) Park (1998) Casey(2001) RuCl 2 (PPh

SLIDE 1

RACEMIZATION OF SECONDARY ALCOHOL

Ph Ph O Ph Ph Ph O Ph H Ru OC CO Ru CO OC H Ph Ph R OH RuCl2(PPh3)3 5 NaOH R OH Ru Cl Ru Cl Cl Cl Park (1998) Ru P(C6H5)3 P(C6H5)3 Cl Ru H Ru Cl Cl Cl Ru cat. Ru cat: + + 5KOH Shovo (1986) Bäckvall (1999) Casey(2001) Bäckvall (1999) Park (2000)

SLIDE 2

DEHYDROGENATIVE TRANSFORMATION OF SECONDARY ALCOHOL

C6H5 OH C6H5 OH >99% ee Cp*RuCl(cod) ligand KOH 2-propanol 50°C, 30 min Ru HN P(C6H5)2

日日日日本本本本化化化化学学学学会会会会第第第第７７７７８８８８春春春春季季季季年年年年会会会会, 1F514 (2000)

ligand P(C6H5)3 ( 1 eq. ) 0% ee 9% ee 98% ee 98% ee 98% ee (C6H5)2P NH2 (C6H5)2P N(CH3)2 (C6H5)2P P(C6H5)2 (C6H5)2P NH(CH3) (H3C)2N NH2 98% ee

SLIDE 3

DEHYDROGENATIVE TRANSFORMATION OF ALCOHOLS

N Ru P H H H R C R' O Ar Ar N Ru P H H H R C R' O Ar Ar EPIMERIZATION OF meso-DIOLS ISOMERIZATION OF ALLYLIC ALCOHOLS LACTONIZATION OF α α α α,ω ω ω ω-DIOLS

SLIDE 4

ENANTIOMER DISCRIMINATION OF SECONDARY ALCOHOL

alcohol:Ru:chiral ligand:KOH = 100:1:1.5:1 R OH CpRuCl(cod) chiral ligand KOH 2-propanol, 30 °C R OH R = C6H5 or n-C4H9 kS/kR = 1.3 kS/kR = 1.8 R = n-C4H9 R = C6H5 chiral ligand N P(C6H5)2 H

S

Ru N P(C6H5)2 amide complex

SLIDE 5

2 4 6 8 20 40 60 80 100 conversion, %

ENANTIOMER DISCRIMINATION OF sym-DIOL

time, h C6H5 C6H5 OH OH C6H5 C6H5 OH OH Cp*RuCl(cod) chiral ligand KOH 2-propanol, 30 °C hydrobenzoin:Ru:chiral ligand:KOH = 100:1:1.5:1 dl meso R,R-diol S,S-diol

R S

chiral ligand N P(C6H5)2 H

SLIDE 6

10 20 20 40 60 80 100 conversion, %

EPIMERIZATION OF meso-HYDROBENZOIN WITH ACHIRAL LIGAND

C6H5 C6H5 OH OH C6H5 C6H5 OH OH Cp*RuCl(cod) ligand KOH 2-propanol, 30 °C hydrobenzoin:Ru:ligand:KOH = 100:1:1.5:1 meso ligand H2N P(C6H5)2 reaction time, h

R S

* * dl

SLIDE 7

2 4 6 8 10 20 40 60 80 100 conversion and ee, %

EPIMERIZATION OF meso-HYDROBENZOIN WITH CHIRAL LIGAND

time, h C6H5 C6H5 OH OH C6H5 C6H5 OH OH Cp*RuCl(cod) chiral ligand KOH 2-propanol, 30 °C hydrobenzoin:Ru:chiral ligand:KOH = 100:1:1.5:1 chiral ligand N P(C6H5)2 H conv. ee

R S R R

meso dl

S

SLIDE 8

SYNTHESIS OF OPTICALLY ACTIVE DIOLs FROM meso-DIOLs

R OH R OH R OH R OH Cp*RuCl(cod) chiral ligand KOH 2-propanol, 30 °C, 4 h conv, % ee, % –(CH2)4– 49 18 99 98

meso-diol:Ru:chiral ligand:KOH = 100:1:1.5:1

chiral ligand N P(C6H5)2 p-CH3-C6H4 conc. 16 91 0.1 M 0.05 M 0.1 M 0.1 M R C6H5 CH3 H

R R R S S

p-F-C6H4 22 85 0.1 M

SLIDE 9

A POSSIBLE MECHANISM FOR EPIMERIZATION

C6H5 C6H5 OH O C6H5 C6H5 OH OH C6H5 C6H5 OH OH C6H5 C6H5 O OH C6H5 C6H5 OH OH meso R,R S,S S R

R R R R S S S S

dl C6H5 C6H5 O OH

S

C6H5 C6H5 O OH KOH 2-propanol 30 °C, 1h S/C = 100