[3,3]-Sigmatropic Rearrangement

Cope rearrangement

Claisen rearrangementg

Claisen Rearrangement

OMeO

O

OOHO

63%Nicolaou, K. C.; Li, J. Angew. Chem. Int. Ed. 2001, 40, 4264.

StereochemistryH

H

OH

H

HO H

H

H

H

RR

O O

R R

HH H

H H H H

Me Me OH

Me

HO H

Me

HMeMeMe Me

O O HH H

H H H H

H

Me Me OH H

O HHMeMe

Me Me

O O HH Me

H

Me

H Me H

MeH

Me Me

Ziegler, F. E.; Piwinski, J. J. J. Am. Chem. Soc. 1982, 104, 7181.

(Anionic) Oxy-Cope Rearrangement

Schreiber, S. L.; Santini, C. Tetrahedron Lett. 1981, 22, 4651.

O

O

O

18-crown-6OO

O

18-crown-6

Aza-Cope Rearrangement

aza-Cope–Mannich

Knight, S. D.; Overman, L. E.; Pairaudeau, G. J. Am. Chem. Soc. 1995, 117, 5776.

Johnson–Claisen Rearrangement

OEtOEt OEt

OHOEt

H+ OEt

OHO

OEtEtO

OH

O

OEt

O

OEt

O

OEt

H

Johnson–Claisen Rearrangement

Takahashi, T. et al. J. Org. Chem. 1986, 51, 3393.

Ireland–Claisen RearrangementLiO TMSO TMSO

LDATHF

–78 ºCO

LiO

Me3SiCl O

TMSO

O

TMSO

O

O

LDA O

LiO

Me3SiCl O

TMSO

O

TMSO

LDATHF/HMPA

–78 ºC

O Me3SiCl O O

Ireland, R. E.; Mueller, R. H.; Willard, A. K. J. Am. Chem. Soc. 1976, 98, 2868.

HMPA: hexamethylphosphoramide

HMPT: hexamethylphosphorous triamide

Stork, G. et al. J. Am. Chem. Soc. 1998, 120, 1337.

Carroll–Claisen Rearrangement

E h Cl i R tEschenmoser–Claisen RearrangementNMe2

OMNMe2

NMOH OMe

OMeOMe

OHO

NMe2MeO

O

NMe2

H

NMe2

O

NMe2

OO

[2,3]-Sigmatropic Rearrangement

Mislow rearrangement

S O S O

[2,3]-Wittig rearrangement

[3,3]-Sigmatropic Rearrangement

C tCope rearrangement

m [m,n]

1 n

[m,n]

suprafacial-suprafacial1'

total number of electrons = (4n + 2) ....... allowedtotal number of electrons (4n 2) ....... allowed

[1,n]-Shift (Suprafacial Shift)....(4n + 2) electrons

Fleming, I. Molecular Orbitals and Organic Chemical Reactions, John Wiley & Sons: West Sussex, 2009.

Wagner–Meerwein rearrangement

2 electrons

cf. BeckmannCurtiusCurtiusBaeyer–Villiger

[1,n]-Shift

Suprafacial Shift....(4n + 2) electrons

Antarafacial Shift....(4n) electrons

R R R

[1,7]-Shift R R R

100 ºC OHHD +

OHD H

OH

Hoeger, C. A.; Okamura, W. H. J. Am. Chem. Soc. 1985, 107, 268.Fleming, I. Molecular Orbitals and Organic Chemical Reactions, John Wiley & Sons: West Sussex, 2009.

4 electrons

Woodward–Hoffmann rule

A ground-state pericyclic change is

symmetry-allowed when the total number of

(4q+2)s and (4r)a components is odd.

Woodward, R. B.; Hoffmann, R. Angew. Chem. Int. Ed. 1969, 8, 781.