160 307 ch 12 reagents and solvents

TMAO (trimethylamine-N-oxide)

-oxidizing agent

-recycles Os(VI) to Os(VIII)

-during OsO4 oxidation of alkene to glycol

NMMO (N-methylmorpholine-N-oxide)

-oxidizing agent

-recycles Os(VI) to Os(VIII)

-during OsO4 oxidation of alkene to glycol

OsO4

-oxidizes alkene to glycol

-concerted cycloaddition rxn

-syn addn

(Li+-Cu(CH3CH2)2 (Lower order lithium organocuperate (in comparison to higher order))

-has side rxns/side prods

(CH3CH2)2Cu(CN)Li2

-Sn2 like, carbanion-like cuperate-c chain initiates backside

-alpha C: retain epoxy O, retain stereochem

-beta C: gains CC bond, invert stereochem

-remember Sn2 solvent; protonating step if prod is ROH

THF (tetrahydrofluoride)

Sn2 solvent

Grignard w epoxide

-1* ROH

-new CC bond extending from grignard c chain ("substrate" like)

KMnO4 w alkene

-alkene oxidation to glycol

-concerted cycloaddtion rxn

-syn addn

H5IO6 (periodic acid)

-cleaves CC bond btwn vicinial OH (glycol)

-cyclic ester int: undergoes spont breakdown by cyclic e- flow initiated by I accepted e- pair from IO bond

-prods: aldehydes and/or ketones + H3IO4 (V)

-glycol struct determines cyclic ester int formation (cis glycol)

sulfonium salt

-protonated sulfide but H replaced by R

-react w nuc in Sn2

-among highest reactive alkylating agents

-releases sulfide + R

-ex.) trimethyloxonium tetrafluoroborate

oxonium salt

-protonated ether but H replaced by R

-react w nuc in Sn2

-among highest reactive alkylating agents

-releases ether + R

-ex.) trimethylsulfonium nitrate

why do intramolecular rxn occur faster than intermolecular?

-reactants are already together

-diffusion and rotation matching is random in soln, in same molecule they dont need to find eachother

intramolecular rxns

-form cyclic products by Sn2

-4 membered least favored

-relative rates (#atoms in ring) 7+ < 4 < 6 < 3 < 5

epoxide structure

-O bond to 2 C bonded together

ether structure

R-O-R

sulfide structure

R-S-R

glycol structure

C chain w 1,2- (vicinal) hydroxyl groups

ether from ROH, RX via RO- int

-rxn w 1* RX yields more major prod

-Sn2 rxn

sulfide from RS, RX, via RS- int

-rxn w 1* RX yields more major prod

-Sn2 rxn

Hg(OAc)2 / (CH3)2CHOH + NaBH4 / NaOH

-ether from alkoxymercuration-reduction of alkene

-ROH solvent (not H2O)

-mark. H addn

H2SO4 / heat / EtOH

-symm. ether from alcohol dehydration

-Sn2 rxn

-restricted to 1 ROH (2, 3* => alkenes)

-harsh conditions: SA, heat

dilute H2SO4 + 3* ROH

-unsymm. ether from alcohol dehydration

-3* ROH, mild conditions (dilute SA, ROH solvent)

-solvent ROH must not form C+ readily (ex. 1* C+ not often formed)

MCPBA (meta-chloroperoxybenzoic acid)

-alkene to epoxide

-concerted electrophilic addn

-syn addn

MMPP (magnesium monoperoxyphthalate)

-alkene to epoxide

-concerted electrophilic addn

-syn addn

peroxybenzoic acid

-alkene to epoxide

-concerted electrophilic addn

-syn addn

halohydrin + base = epoxide

-cyclization of halohydrin

-intramolecular rxn

-C-O and C-X bonds must be anti for intram step

-alpha c: invert stereochem.

RX + ether

-ether cleavage

-X pref. more substituted C (X is high EN)

-prod: alkyl group -> alkyl halide

-protonated ether good LG

-3* alkyl: Sn1 like rxn, C+ int.

-2* alkyl: Sn1 or Sn2

-1* alkyl: Sn2

ring opening: basic

-only epoxides, no ethers undergo ring opening in basic conds (signif angle strain makes more reactive)

-alpha c: Nuc pref, less hindered, invert stereochem

-beta c: retain epoxy O, more hindered, invert stereochem

-double inversion!

ring opening: acidic (trace SA)

-alpha c: Nuc pref, more hindered, invert stereochem

-beta c: retain epoxy O, less hindered, retain stereochem

-unsymm epoxides 1 2 C give mixtures of prods

-epoxide protonation first

-Nuc addn is Sn2 like