orgo 2 exam 1

Williamson Ether Synthesis

Begin with alcohol, use base and alkyl halide

Only Sn2 (primary carbons)

W.E.S retrosynth

Try with cleaving all bonds next to O, and whichever mechanism isn’t on a primary carbon, it’s not right (sn2)

Base in W.E.S.

Used to deprot.

Nuc goes after E+

True

Ether Cleavage

Begins w ether

Uses HI or HBr

Ether attacks first, as I/Br are good L.G., and then they come back to attack

Thioethers

S is a good L.G.

Silyl Groups (OTIPS)

ONLY for alcohols

protects the less stable OH, can be removed with TBAF

Ex) 1. OTIPS 2. KOH 3. CH3CH2Br 4) TBAF

Epoxides

2 ways to make:

1) MCPBA

2) Halohydrin cyclization

MCPBA

Attacks more e- dense alkene (double bond)

Ex: two F’s near the double bond, they’re pulling all the e- away from double bond so that is LESS dense (would not attack)

Halohydrin cyclization

Same as W.E.S. But the alkyl halide is within the molecule itself

Acidic epoxide opening

1. Protonate

2. Expoxide does the attacking - attacks H

3. H2O, OH, etc attackers MOST substituted C

4. deprot

Basic Epoxide Opening

1) strong nuc does the attacking

2) attacks LEAST substituted C

3) protonate w H2O

Basic

Strong nuc

NaOH

Basic

CH3OH

Acidic

MgBR (grignards)

Basic/strong nuc

C-C

1200

C=C

1660

C_=C

2200

Conjugation

Lowers frequency

Isolated C=C

1640-1680

Conjugated C=C

1620-1640

Aromatic C=C

1600

Sp3, 2800-3000

Sp2, 3000-3100

Sp, 3300, sharp

OH

3300, broad, rounded tip

R2NH

Secondary - 3300, broad with one sharp spike

RNH2

Primary, 3300, broad with two sharp spikes

R3N

Tertiary, no signal bc no H

C=O of ketones, aldehydes and Carboxylic acids

1710

Conjugated carbonyls

1700 ish