M10: New Synthetic Methods I

Horner-Wadsworth-Emmons
[image]
Peterson Reaction
[image]

Julia Olefination

 

(SET)

[image]
Julia-Julia Olefination
[image]

Ramberg Backland Olefination

(trans)

[image]

Pummerer Reaction

 

(HEMI THIOACETAL)

Like the Swern Oxidation.

BUT.

The BASE reacts first to kick out the Cl-

Then the ALCOHOL reacts.

HEMI THIOACETAL FORMED.

Sulfide Mediated Epoxidations
[image]

Sulfoxide Elimination

 

(Se does the same)

[image]

Allylic Sulfoxide Rearrangement

 

(Se does the same!)

[image]
Ph-Se-Cl addition to double bonds
It makes a selenium epoxide…

C-Se bond is weak, can be removed by Bu3SnH and AIBN

Selenium Dioxide Allylic Hydroxylation
[image]

Barton Dehydroxylation

 

(removes alcohol)

[image]

Dess Martin Oxidation

 

(alcohol to ketone)

[image]

TEMPO-BAIB Oxidation

 

(alcohol to ketone)

[image]

Mitsunobu

 

(alcohol to ester)

[image]
Property of silicon…

Forms cations in the beta position

 

(C-Si sigma overlaps with p orbital)

 

(and alpha anions)

Sakurai Reaction
[image]

Hydroboration

 

(addition of C=O across a diene)

Thexyl borane forms 5 mem ring

CO attacks the B

Migration to form 6 mem ring

O attacks B to form 3 mem ring

Migration to neutralise B and form a 5 mem ring

H2O attacks B, standard hydroboration

Brook Rearrangement

 

(SiR3 moves to alcohol O to be replaced by E+)

[image]
What else can Et3SiH do?

Reduce things as H!

 

Possible to have H+ and H in the same reaction…

Ways to remove Si protecting groups?

 

(3 ways…)

TBAF

 

Bu4N+F

 

HF, pyrimidine buffer (the classic)

R3Sn-H

 

This is mentioned in the course…

Just revise radical stuff… -_-:;

 

C3, M10 p21 etc.

Fleming Tamao Reaction

 

(removes silicon)

 

NO NEED TO KNOW MECH!!!

R–Si(PhMe2) -> R–OH

 

Reagents:

Hg(OAc2) mercury

RCO3H mcbpa

 

Retention of configuration

WH: Torquoselectivity in electrocyclic reactions

 

How do EDG and EWG behave?

EDG rotate outwards

 

EWG rotate inwards

 

Normally, electronic effects dominate sterics

WH: Electrocyclic

 

Nazarov Cyclisation

Double alpha-beta unsaturated carbonyl

 

Forms pentane

 

CON under heat and Lewis Acid

WH: Electrocyclic

 

Ketene Cyclisation

 

(HARD)

Not [2+2] or stepwise

 

Draw the orbitals…it’s that weird one.

;

SYN.

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