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Reading a synthesis like an argument

Science · Chemistry · ages 23-24

Name ______________________ Date ____________

How can you reconstruct a plausible plan from a forward synthesis scheme?
- Reverse every arrow to prove the authors' original thinking
- Infer disconnections and functional-group changes
- Rank printed yields without examining molecular changes
Which evidence supports both product identity and the amount obtained in a reported synthesis?
- Measured yields with suitable structural data
- Measured yields without checking any product identity
- Structural assignments without measuring any isolated yields
Publication of a synthesis proves that its route is optimal for every goal and scale.
Circle one: True False
What should you use to assess the justification for a stereochemical assignment?
- Data and methods matched to the stereochemical claim
- Chiral peak areas alone for absolute configuration
- NOE distances alone for every absolute configuration
A route deliberately protects one alcohol so another can form the intended bond selectively. How should that protection be classified?
- A repair that cannot contribute to any route strategy
- Evidence that the product structure has been disproved
- A planned selectivity tool within the route
A scheme prepares fragments A and B separately, then joins them late. What route organisation does this suggest?
- A linear plan extending one intermediate at every step
- A convergent plan that joins prepared fragments
- A one-pot plan containing no separately prepared fragments
Validated quantitative chiral chromatography separates a product's two enantiomers, but no configuration reference is available. What can this measurement establish?
- Enantiomer ratio, not absolute configuration
- Absolute configuration from peak order without a reference
- Absolute configuration of every centre from peak areas
An alternative disconnection adds two steps, but its yields have not been measured. How should you compare it with the published route?
- Declare it inferior because extra steps always lower output
- Declare it superior because the proposed cut looks more direct
- State added steps and obtain yield data before ranking

Answer key

For grown-ups. Fold this page away before handing over the rest.

Reading a synthesis like an argument W1-mt_Eu3Id8NMrH-s1

Infer disconnections and functional-group changes · Working backwards gives a possible plan. It does not prove the authors' original reasoning.
Measured yields with suitable structural data · Structural data address product identity. Measured yields address the amount obtained. Neither alone supports both claims.
False · A paper reports a route and evidence. Optimality depends on the goals, alternatives and scale being compared.
Data and methods matched to the stereochemical claim · Relative configuration, absolute configuration and enantiomer ratio require suitable evidence and interpretation. One measurement does not establish every claim.
A planned selectivity tool within the route · The protection was planned to enable selective reaction. It can support strategy rather than being an automatic repair.
A convergent plan that joins prepared fragments · Separate preparation branches followed by joining suggest a convergent plan.
Enantiomer ratio, not absolute configuration · Validated quantitative responses give the enantiomer ratio. Absolute assignment requires a reference or another suitable method.
State added steps and obtain yield data before ranking · The extra steps are known; the yield effect is not. Compare routes against the same goals and label estimates as uncertain.