Concepts in organic synthesis: retrosynthesis, disconnection and synthons - One Line Questions
1.
The 'carbonyl group' is often a target for disconnection. What are common synthons derived from a carbonyl group? —
An acyl anion equivalent and an alkoxy cation equivalent.
2.
The disconnection of an ester (R-COO-R') typically leads to synthons related to: —
A carboxylic acid and an alcohol.
3.
The disconnection of a C-N bond in an amide (R-CO-NR'R'') typically leads to synthons related to: —
A carboxylic acid and an amine.
4.
What is the common synthetic equivalent for a carboxylate synthon (RCOO-)? —
All of the above.
5.
What is the relationship between a disconnection and a forward reaction? —
A disconnection is the reverse of a forward reaction.
6.
What does the term 'reductive disconnection' imply? —
A disconnection that leads to synthons requiring reduction in the forward synthesis.
7.
What does the term 'oxidative disconnection' imply? —
A disconnection that leads to synthons requiring oxidation in the forward synthesis.
8.
Which type of synthon is represented by a carbene (R2C:)? —
A neutral synthon with divalent carbon.
9.
A disconnection that results in a synthon with a positive charge on carbon is typically considered: —
An electrophile synthon.
10.
What is a 'chiral auxiliary' in the context of stereoselective synthesis, often considered during retrosynthetic planning? —
A molecule temporarily attached to control stereochemistry.
11.
In the context of retrosynthesis, what is a 'telescoped' reaction sequence? —
A sequence where multiple reaction steps are performed in the same pot without isolation of intermediates.
12.
A disconnection that aims to simplify a cyclic structure often involves breaking: —
A single C-C bond to open the ring.
13.
What is a 'synthon' in the context of retrosynthesis? —
An idealized, charged fragment resulting from a disconnection.
14.
Which of the following is a valid synthetic equivalent for an acyl cation synthon (RCO+)? —
An acid chloride (RCOCl) or anhydride.
15.
The 'Wittig reaction' is a well-known method to form C=C bonds. In retrosynthesis, its disconnection leads to synthons related to: —
An aldehyde/ketone and a phosphonium ylide.
16.
Which of the following is a common synthetic equivalent for an alkyl anion synthon (R-)? —
An organometallic reagent (e.g., Grignard, organolithium).
17.
A disconnection that results in a synthon with a negative charge on carbon is typically considered: —
A nucleophile synthon.
18.
What does the term 'strategic disconnection' refer to in retrosynthesis? —
A disconnection that simplifies the molecule significantly or leads to readily available starting materials.
19.
The 'Grob fragmentation' is a specific disconnection strategy for: —
Cyclic compounds with specific arrangements of heteroatoms.
20.
Which of the following is NOT a primary consideration in choosing a disconnection strategy? —
The color of the target molecule.
21.
What is a 'functional group interconversion' (FGI) in retrosynthesis? —
Changing one functional group into another.
22.
What does a 'temporary disconnection' strategy involve? —
Introducing a functional group that can be easily removed later to facilitate disconnection.
23.
What is a 'convergent synthesis' strategy, often planned using retrosynthesis? —
Synthesizing different fragments separately and then joining them.
24.
What is a 'linear synthesis' strategy? —
Building the molecule step-by-step, adding one piece at a time.
25.
The 'aza-Cope rearrangement' is a reaction that might be considered in retrosynthesis for forming: —
C-N bonds and rearrangements.
26.
In retrosynthesis, the term 'telescoping' when applied to synthons means: —
Using a synthon that can represent multiple functionalities simultaneously.
27.
When planning the synthesis of a complex molecule, retrosynthesis helps in: —
Breaking down the complexity into simpler steps.
28.
Which type of disconnection is often used to form C-C bonds? —
Disconnection of a C-C bond.
29.
The disconnection of an amine often leads to synthons that can be formed via reactions involving: —
Nucleophilic attack on alkyl halides or carbonyls.
30.
When a disconnection leads to a synthon that is itself complex, what is the next step in the retrosynthetic analysis? —
Apply retrosynthesis to the simpler fragments.
31.
Which of the following is a key advantage of E.J. Corey's logic in retrosynthesis? —
Emphasis on stereochemical control and efficient bond formation.
32.
The process of identifying potential disconnections in a target molecule is known as: —
Retrosynthetic analysis.
33.
A disconnection that simplifies a molecule by removing a functional group and replacing it with a hydrogen atom is generally termed: —
A reductive disconnection.
34.
What is the main advantage of using retrosynthesis? —
It simplifies complex synthetic problems.
35.
The disconnection of a hydroxyl group from an alcohol often leads to synthons that can be formed via: —
Nucleophilic addition to carbonyls or alkylation.
36.
The disconnection of an alkene often leads to synthons that can be formed via: —
Elimination reactions.
37.
Consider a disconnection that breaks a C-X bond where X is a halogen. What are the potential synthons? —
R+ and X-
38.
Consider the disconnection of an ether (R-O-R'). What are the likely synthons? —
RO- and R+
39.
The concept of 'synthon equivalence' is crucial because: —
Synthons are usually unstable and cannot be directly used.
40.
What is the synthetic equivalent of a synthon? —
The actual reagent used in the forward synthesis that corresponds to the synthon.
41.
In retrosynthesis, what does a 'disconnection' represent? —
The breaking of a bond in the target molecule to simplify it.
42.
When performing retrosynthesis on a molecule with multiple functional groups, it is often strategic to disconnect: —
A bond that creates two simple fragments.
43.
What is a 'stereochemical outcome' that is often a crucial consideration during retrosynthetic planning? —
The arrangement of atoms in three-dimensional space (e.g., enantiomers, diastereomers).
44.
What is the 'target molecule' in retrosynthetic analysis? —
The desired final product of the synthesis.
45.
Which of the following best describes the 'thermodynamic' consideration in choosing a disconnection? —
The stability of the synthons and intermediates formed.
46.
Which of the following is a common characteristic of synthons? —
47.
What is the primary role of 'protecting groups' in the context of retrosynthesis and forward synthesis? —
To temporarily mask a reactive functional group to prevent unwanted reactions.
48.
What is the purpose of establishing 'orbittals' in some advanced retrosynthetic planning? —
To define the stereochemical relationships between atoms.
49.
What is the primary goal of retrosynthesis in organic chemistry? —
To devise a synthetic route by working backward from the target molecule.
50.
When a disconnection breaks a molecule into a nucleophile synthon and an electrophile synthon, the corresponding synthetic equivalents are often: —
A nucleophile and an electrophile.