#multistep synthesis

[scimajorlinks-blog]

Some oddball reaction types to help when you're stuck.

This is a professor’s final review I found online, and it explains everything step by step to make sure you understand why it works that way. Very helpful!

[scimajorlinks-blog]

Multistep Synthesis Rxn Notes

For stereospecific, use Sn2 (ex: cis -> trans)

For racemic mixture, use Sn1

In Sn1, there can be a hydride or methyl shift because 3o cation is more stable

E1 & Sn1 happen simultaneously

Zaitev’s Rule - more substituted alkenes form predominantly

E2 is also stereospecific

Dibromide elimination is done with Zn in CH3COOH

Dehydration of alcohol is an E1 rxn -> alkene

Add H2SO4 which protonates the OH group

H2O leaves then takes another proton to create the double bond

Make ether from Sn2

Simplest electrophile - H+

Addition rxn - Electrophile then Nucleophile

To make a diol -

anti-formation

1. CH3CO3H

2. H3O+

syn-formation

react with: OsO4, NMO

solvent: H2O, tert-butanol

Form primary alcohol from formaldehyde:

- Form secondary alcohol from aldehyde:

- Form tertiary alcohol from ketone:

Can only oxidize 1o or 2o alcohol with CrO2(OH)2 - end up with >C=O

Replace 1o or 2o OH group with a halogen (X group) by using SOCl2 to chlorinate or PBr3 to boronate with inverse stereochemistry because it is an Sn2 rxn

- CN- attacks less substituted Carbon

- Alcohol to ketone, use Na2Cr2O7 

- Ketone to R group with OH and CH3 by using CH3MgBr and H3O+ 

[scimajorlinks-blog]

A practical guide to tackling undergraduate multistep synthesis questions