Nucleophile addition to carbonyls

purpsose of the protecting group

A protecting group turns a reactive functional group (like a ketone or aldehyde) into an unreactive group.

This is often done to protect the carbonyl during a multi-step synthesis when you want to avoid reactions on the carbonyl.

are protecting groups reversible

Yes, protecting groups are designed to be removed after specific reactions are completed, allowing the original functional group to be restored.

how is the protiectign group removed

the protecting group is removed be H3O+ to restore the original carbonyl group.

protective group for ketone

ethylene glycol (HOCH₂CH₂OH) and acid (H+) to form acetal or ketal

Protecting Group for Alcohols

• put on TBDMS-Cl and (CH3CH2)3N to protect alcohol

  • perform a SN2 reaction

• protecting group is taken off by (CH3CH2CH2CH2)4N+ F-

wittig reactions what are the reactants and products

reactants

• carbonyl compound

  • ketone or aledhydes

• product

  • alkene (replace the oxygen with the R group off the ylide and make sure its and alkene and always remember carbon has four bonds so may have to change the R group from CH3 to CH2)

  • PH3PO

• reagent

  • phsophonium ylide (Ph3P with any alkyl halide) its a neutral species with a + and - charges on adjacent atoms

  • the P has a posotive charge adn the R group has a negative chage

ylide formation reactants and products

reactants

• Ph3P

• alkyl halide

solvelnts

• strong bases

  • BuLi

  • NaH

  • NaOEt

  • organolithium

• product

  • ylide product with the R group off of the alkyl halide and the - charge on the R group and th posotive charge on the phosphorus

hard nuleophiles are ______ and attacks the ____ and it does what type of addition

irreversible and attack the carbonyl carbon and it does a 1,2 addition

soft nuclophile are _____ and attacks____ what type of reaction is it

it is reversible reaction

and it attacks the beta carbon

and it does a 1,4 addition

Hard nucleophile characteristics

• smaller in size

• has negative chage

  • localized in one atom

• not polarizable

• tend to be more reactive and less stable nucleophiles

soft nucleophiles

• neutral or has - charge

  • negative chage is likley deloclaized

• larger

• more polarizable

• resonsance stabalized

  • tend to be less reactive and more stable nucleophiles

hard nucleophiles examples

• organolithium

• griginard reagent

• LiAlH4 “LAH”

• fluroide

soft nucleophile examples

• alcohols

• cyanide

• cl-,br-,I-

• enolates

• cuperates (gilman reagent)