Organic Chemistry II – Reaction Mechanisms and Problem Sets/Organic Chemistry II | Lectures 1-38 | All Course Material LATEST WITH COMPLETE SOLUTION RATED A+

Organic Chemistry II – Reac on Mechanisms and
Problem Sets/Organic Chemistry II | Lectures 1-38 | All
Course Material LATEST WITH COMPLETE SOLUTION
RATED A+
adding 1 mol NaNH2 to an alkyne

removes the H off the C and leaves two lone pairs and a nega ve charge

We use this so we can add things to the end of a triple bond (See pick) through an SN2 reac!on

t-buOK

Make an alkene from an alkane

a'acks least substuited carbon

How to form an epoxide from an alkane with Br

1. t-buOK

--- uses Br to form alkene

2. RCO3H

--- convert the alkene to an epoxide (RACEMIC)

N.B. this example uses dif chemicals

Br2, hv

Bromina!on of Alkanes

!. Alkane
2. Add Br to the most subs!tuited carbon

H3O+ excess and protec!ng group

This just means you take off the protec!ng group at the end

1. Br2
2. NaNH2 (2 or 3 mol)

,turns alkenes into alkynes

changes depending on whether its internal alkyne

Retrosynthesis of chair confirma!on to fragment

Even if there are mul!ple OHs, we know the one that was the DP is the one next to the O in the
ring

In chair confirma!on, we can see the stereochemistry of the subs!tuents (Wedged or dashed) if
it is poin!ng up or down

--- N.B. when we turn it from a ring into a line, the stereochemistry we keep is NOT the
wedged/dashes but whether it is R or S

NaOH, H2O

regioselec!ve

Markov

on the most hindered carbon

non markov

on the least hindered carbon

ATTACK OF THE NUCLEOPHILE

you can also write "make a bond"

When the nucleophile a'aches itself to the electrophile

1. BH3
2. H2O2, NaOH

add OH to least subs!tuted C on the alkene (non-markov)

Conc H2SO4

E1
alcohol to alkene

Write SN2 or

simultaneous a'ack of the nucleophile and departure of leaving group

Organometallic compounds

,compounds that contain carbon-metal bonds

Ex.

Hemoglobin has Fe

Chlorophyll has Mg

IMPORTANT: in almost all other bonds we look at (ex. C-O), the other atom is more
electronega!ve (O). With ORganiometallic compounds, the carbon is more electronega ve
than metal and has a par al - charge. Carbon is the nucleophile.

WE focus on

--- Grignard Reagents

--- Organolithium Reagents

--- Gilman Reagents

(all are nucleophiles)

Grignard and Organolithium are strong bases

FORMING AN EPOXIDE

Grignard reagent

Alkyl-MgBr

Prepara!on of Grignard Reagent

Mg, Ether

1) Start with any Haloalkane (can be primary, secondary, ter!ary, etc..)

2) Add Mg with Ether Solvent

3) Mg will replace the posi!on of the halogen

Organolithium reagents

Alkyl-Li

Prepara!on of Organolithium Reagent

2 Li, pentane

1) Start with any Haloalkane (can be primary, secondary, ter!ary, etc..)

2) Add 2 Li with Pentane Solvent

, 3) One of the Li will replace the posi!on of the halogen, and the other will form a bond with the
loose halogen

FORMS SIDE PRODUCT OF LiBr which is why we need 2 Li)

Gilman Reagent

(Alkyl)2-CuLi

The alkyl R group needs to be minimally sterically hindered, 4 op ons:

--- primary haloalkane

--- primary allylic haloalkane (the primary haloalkane is next to a C with a double bond

--- vinylic haloalkane (the carbon with the halogen also has a double bond

--- aroma!c haloalkane (A'ached to a ring??)

Prepara!on of Gilman Reagent

A) 2 Li, pentane

B) Cu, Ether

Start with 2 mol of Organolithium Reagent

1) Start with one of four Haloalkane

2) Add 2 Li with Pentane Solvent

3) One of the Li will replace the posi!on of the halogen, and the other will form a bond with the
loose halogen

x2

4) add CuI in Ether solvent to two copies of the O Reagents

--- Cu takes the place of one of the Li, and the other one binds to the free I

Grignard and Organolithium reagents react with

A)

Gilman Reagents don't react with

a) aLDEHYDES/kETONES (not nucleophilllic enough)

Nucleophilic Ring Opening of Epoxide using Grignard/Organolithium Reagent

A) add