C=C bond forming reactions 1.  Elimination X=halogen, sulfonate, amminium, sulfonium : basic condition --- anti elimination X=OH : acidic condition --- rearrangement occurs

1.  Elimination

2. Pyrolytic syn-elimination --- retro-ene reaction 300 ㅇ C 100 ㅇ C Chugaev reaction 100 ㅇ C

2. Pyrolytic syn-elimination --- retro-ene reaction < 100 ㅇ C Room Temp. General procedure

3. Fragmentation  fragmentation t-BuLi, ether 예외

Grob fragmentation : ACIE, 1969, 8, 535

4. Others From Hydrazone From Diol Corey, TL, 1982, 23, 1979 Bamford-Stevens rxn. JCS 1952, 4735 Shapiro rxn. Org. Rxn. 1976, 23, 405

3. Wittig Reaction Chemistry of Ylides Ylide : Formation of phosphorous Ylides R= Alkyl : base = BuLi, LDA E.W. NaOH

3. Wittig Reaction Stereoselectivity with stabilized ylides --- trans major with non-stabilized ylides --- cis major non-polar solvent, salt free condition (HMPA) destabilizing phosphorous -- this is not exactly correct

with non-stabilized ylides 80%, >98% cis

mechanism + betain [2+2] cis olefin

Schlosser modification -70 o C trans:cis > 97:3 ACIE, 1966, 5, 126

For Hindered carbonyls Modhephene Conia procedure Alcohol ensures the equilibrium between ketone and enolate Anion of ylide 87% Corey, TL, 1985, 26, 555

with stabilized ylides mechanism

Effect of  oxygenation and protic solvent DMF 86 : 14 CHCl 3 40 : 60 CH 3 OH 8 : 92 Helv. 1979, 62, 2091 THF 6 : 94 THF-MeOH (1:1) 93 : 7 TL. 2004, 45, 3925

Conjugate addition

3.2 Wadsworth-Honer-Emmons reaction W = CN, COOR, CHO, SO 2 Ph, C(O)R, Ph, vinyl not with Alkyl or H Does not eliminate spontaneously ! E-selective trans Water soluble !

Preparation of the reagent Arbuzov reaction : Perkow reaction

cis selective olefination W.C. Still, TL, 24, 4405(’83) Z:E = 50:1 JOC, 64, 8406 (’99) Z:E = 9:1

Stereo-selective olefination : Horner-Wittig reaction R’COOEt

Enantio-selective olefination Hannesian, TL, 33, 7659 (1992) Masamune, TL, 37, 1077 (1996) 92 : 8 > 99 : 1

4. Peterson olefination Gillman, JOC, 27, 3647(’62) Peterson JOC, 33, 780 (’68)

and its diastereomer !

5. Julia coupling trans major 2 ~ 3 step sequence ! One step via

5. Julia coupling trans major TL, 1545(1975)

6. Ramber-Backlund reaction 32 – 52 % JACS, 114, 7360(’92) 94 %

7. McMurry Coupling Pinacol coupling Mg SmI 2 Mg-TMSCl 77%, E:Z = 7:3 McMurry, Chem. Rev. 89, 1513 (’89) 56% 38% TL. 24, 1885 (’83) Ziegler, JOC, 47, 5229 (’82)

8. Neutral methylenation a. Oshima-Lombardo reagent TiCl 4 -Zn-CH 2 I 2 TL, 2417(’78) 90% JACS, 108, 7408 (’86) JACS, 119, 1127 (’97) b. Takai alkenylation JACS, 115, 2268 (’93)

9. Transition metal chemistry : neutral olefination a. Tebbe’s reagent Neutral, reactive Unstable, limited X= H, R Working through Metathesis Tebbe, JACS, 100, 3611, 1978 X= OR, SR, NR 2 Pine, Grubbs, JACS, 102, 3270, 1980

b.Petasis reagent R can be TMS JACS, 112, 6392, (1990) 82% TL, 36, 3619 (1995)

c. Olefin Metathesis Grubbs, Tet., 60, 7117, 2004 Metathesis Olefin Metathesis JACS, 90, 4133, 1968 JACS, 92, 528, 1970

JACS, 108, 855, 1986

T, 55, 8141, 1999 Schrock cat. Reactive, unstable Grubbs 1 st gen.cat./ 2 nd gen.cat. Reactive, stable mechanism

Nicolaou, JACS. 1997, 119, 7960 Smith III, JACS. 2000, 122, 4985

Synthesis of Epoxides a. Sulfur ylide chemistry Sulfonium salt Sulfur Ylide Corey, JACS, 87, 1353, 1965

C. Johnson, JACS, 95, 7424, 1973 Thermodynamic kinetic

Cyclopropanation with Sulfur ylide 81% 89% Soft Nu Hard Nu 75%

C. Johnson, JACS. 1973, 7424 Trost, JACS 1973, 962 JOC. 1989, 4222 Asymmetric Epoxidation with Sulfur ylide 97% e.e. Tet. Asym. 1996, 1783

Catalytic Asymmetric Epoxidation with Sulfur ylide

Application 배임혁, ACIE, 42, 3274 (’03) 배임혁, Tet., 60, 9725 (’04)

Synthesis of Epoxides b. Darzen Condensation

Asymmetric Darzen Condensation A. Ghosh, OL, 6, 2725 (’04) Extension of the reaction Org. Syn., Coll V 4, 459, (’63)

Homework Chapter 2 : 4, 7, 14, Due : May, 11