Reading a Total Synthesis as an Argument · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Reading a synthesis like an argument

Science · Chemistry · ages 23-24
Name ______________________   Date ____________

  1. 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

  2. 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

  3. Publication of a synthesis proves that its route is optimal for every goal and scale.

    Circle one:   True   False

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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
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Answer key

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

Reading a synthesis like an argument W1-mt_Eu3Id8NMrH-s1

  1. Infer disconnections and functional-group changes · Working backwards gives a possible plan. It does not prove the authors' original reasoning.
  2. Measured yields with suitable structural data · Structural data address product identity. Measured yields address the amount obtained. Neither alone supports both claims.
  3. False · A paper reports a route and evidence. Optimality depends on the goals, alternatives and scale being compared.
  4. 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.
  5. 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.
  6. A convergent plan that joins prepared fragments · Separate preparation branches followed by joining suggest a convergent plan.
  7. Enantiomer ratio, not absolute configuration · Validated quantitative responses give the enantiomer ratio. Absolute assignment requires a reference or another suitable method.
  8. 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.
Worksheet · LightMySky