RINGOPENING OF EPOXIDES WITH ALCOHOLS R H H C R O H + - - PowerPoint PPT Presentation

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ring opening of epoxides with alcohols
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RINGOPENING OF EPOXIDES WITH ALCOHOLS R H H C R O H + - - PowerPoint PPT Presentation

Nov 30, 2022 121 likes •228 views

RINGOPENING OF EPOXIDES WITH ALCOHOLS R H H C R O H + + H Nu Nu M M L L + N EWG N H H R R R + H H C O L: N, P : substrste H H this work OCH 3 OH O cat + CH 3 OH OH +

slide-1
SLIDE 1

N M L Nu H H H C R R EWG H O R R O CH3OH R R OCH3 OH OH OCH3 cat + + H H

RING–OPENING OF EPOXIDES WITH ALCOHOLS

this work δ– δ– δ+ δ+ L: N, P H O C H R R M L N Nu H δ+ δ+ : substrste H δ– δ–

slide-2
SLIDE 2

O N H Ru N Ts arene–Ru complex N H2 Ru N Cl Cp*RuCl complex Ts = p-CH3C6H4SO2 CH3OH OCH3 OH OH OCH3 cat CH3OH 50 °C, 24 h A B Cp*RuCl/KOH cat KOH

REACTION OF STYRENE OXIDE WITH METHANOL

conv, % 82:18 33:67 50 31 82 arene–Ru Ru cat: + + A:B yield, % 90:10 epoxide:CH3OH:cat = 50:500:1 29 31 97 product

slide-3
SLIDE 3

C6H5 + ROH epoxide:ROH:cat = 50:500:1 50 °C, 24 h

REACTION OF STYRENE OXIDE WITH ALCOHOLS

Ru cat (CH3)3COH C6H5 C6H5 OR OH + OH OR A B CH3OH ROH Ru cat: Ru[(S,S)-Tsdpen](p-cymene) CH3CH2OH yield, % A byproducts B byproducts: C6H5 OH C6H5 OH 26 1 <1 <1 22 1 34 25 O ROH

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SLIDE 4

LIMITATION

C6H5 C6H5 C6H5 O O O O O reactive inert inert inert

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SLIDE 5

REACTION OF rac-STYRENE OXIDE WITH METHANOL

O epoxide:CH3OH:cat = 50:500:1 CH3OH OCH3 OH OH OCH3 + 95:5 * * 20% yield 68% ee (R) racemate 34% conv 50 °C, 6 h CH3OH (S,S)-Ru cat: Ru[(S,S)-Tsdpen](p-cymene) (S,S)-Ru cat + N H Ru N Ts C6H5 C6H5 A B

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SLIDE 6

REACTION OF (S)-STYRENE OXIDE WITH METHANOL

O 50 °C, 24 h epoxide:CH3OH:cat = 50:500:1 + OCH3 OH A Ru cat Ru[(S,S)-Tsdpen](p-cymene) Ru[(R,R)-Tsdpen](p-cymene) Ru(Ts-en)(p-cymene)

S

>99% ee CH3OH yield, % ee, % (config) yield, % product (A) recovered epoxide

R

Ru cat CH3OH OH OCH3 + B * 9 6 (R) 58 67 95 (S) 97 (S) 68 31 27 40 (R) 76 (R) 63 (R) ee, % (config)

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SLIDE 7

O solvent epoxide:solvent:chiral cat = 50:500:1 50 °C, 24 h

S

O chiral Ru cat C6H5 N H Ru N Ts Ts = p-CH3C6H4SO2 solvent ee, % (config) yield, % CH3OH C6H6 (CH3)3COH chiral Ru cat: C6H5 * * chiral Ru cat

RACEMIZATION OF (S)-STYRENE OXIDE

S,S R,R CH3OH C6H6 (CH3)3COH S,S R,R S,S R,R 9 58 95 97 >99 >99 5 (R) 97 (S) 14 (R) 99 (S) 57 (R) 20 (R) recoverd epoxide

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SLIDE 8

O cis epoxide:CH3OH:Ru= 50:500:1 O cis trans O (±)-trans O CH3OH 50 °C, 24 h CH3OH 50 °C, 24 h 14% yield 19% ee

cis–trans ISOMERIZATION OF STILBENE OXIDE

no reaction 14% conv (S,S)-Ru cat (S,S)-Ru cat (S,S)-Ru cat: Ru[(S,S)-Tsdpen](p-cymene)

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SLIDE 9

OCH3 OH O[Ru] SN2 SN1 OCH3 OH

R S

CH3OH CH3OH O[Ru]

R

SUMMARY

O[Ru] CH3OH