Carbon to Carbon bond formations Flashcards
Why is carbon to carbon bond formation so important?
Compounds are synthesised in nature by C-C bond formation
What reaction is one of the classical ways to make carbon-carbon bonds?
The aldol reaction
What type of media does the aldol reaction come from?
Acidic or basic
What are the reagents for an aldol reaction?
OH- OR H+
H2O
Then heat after the intermediate is formed
When carbonyl compounds are treated with a base, what do they form?
The Enolate
Carbonyl compounds have another form, what is this called?
Tautomeric form (enol)
(Tautomers are isomers of a compound which differ only in the position of the protons and electrons)
How can the -ve charge on the carbon of the enolate be stabilised?
By resonance
DONT DO THIS FOR EXAM AS NEGATIVE NEEDS TO BE SHOWN
Whats the mechanism for the base catalysed aldol reaction?
What happens in the first stage of the base catalysed aldol reaction?
What happens in the second stage of the base catalysed aldol reaction?
What happens in the third stage of the base catalysed aldol reaction?
What type of reaction is the first step of the TCA cycle?
Aldol reaction
The aldol mechanism in citrate synthesis
Whats the mechanism of the acid catalysed aldol reaction?
What happens in each stage of the acid catalysed aldol reaction?
Whats more nucleophilic, an enol or an enolate?
Why can it still be used in an acid catalysed reaction?
An enol is not as nucleophilic as an enolate, but is sufficiently reactive to attack a protonated carbonyl compound
What mechanism does elimination in acid- catalysed aldol chemistry occur via?
E1 in acid
E1cB in base
Draw out the Claisen ester condensation reaction between 2 esters
Draw the Intramolecular Claisen ester condensation reaction
Draw the mechanism of the Claisen ester condensation reaction?
And what occurs in each step
Whats a retro-aldol reaction?
Retro-aldol reaction: A reaction in which a β-hydroxy carbonyl compound decomposes into an aldehyde or ketone, plus another carbonyl compound. … This β-hydroxy ketone can be decomposed back into acetone and acetophenone in a base-catalyzed (or acid-catalyzed) retro-aldol reaction.
Give an example of when the enzyme aldolase is used in a reaction?
What type of reaction is this?
Terpenes such as vitamin A are synthesised from what?
dimethylallyl pyrophosphate
The construction of an Isoprene unit begins with what type of reaction?
A Claisen reaction
How is the mechanism of a Claisen reaction different when constructing an isoprene?
It uses a thioester rather than a carboxylic ester
Draw out the mechanism of the construction of an Isoprene
- include the by products
- structure of intermediates and products
Whats the aldol reaction an important method for?
What does the Claisen reaction occur between?
What is the mechanism similar to?
