Planning the way back

Science · Chemistry · ages 22-23

Name ______________________ Date ____________

What does symmetry buy in a synthesis plan?
- Fewer distinct steps
- Larger reaction flasks
- Faster stirring
How should candidate disconnections be ranked?
- By skeletal simplification
- By how easy each is to draw
- By how many steps each adds
A convergent route joins fragments of similar size late in the synthesis.
Circle one: True False
A cut you want is blocked by the group sitting there. What opens it?
- Heating the flask longer
- Swap the group first
- Adding more solvent
Two steps run at 0.9 yield each. What is the overall yield?
Answer: ______________
Two routes use the same steps. One runs six steps in line, the other joins two three-step branches. Which gives more product?
- The six-step line, it looks simpler
- Both give exactly the same
- The branched route
Two branches are ready: one took two steps, the other took seven. What should you suspect?
- The long branch sets the loss
- The short branch must be wrong
- Branch lengths never matter
Handed a polycyclic target, a student cuts a side chain first. What is the strategic error?
- Side chains are never cut
- Almost no simplification
- Rings must never be split

Answer key

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

Fewer distinct steps · One operation can install the same feature twice.
By skeletal simplification · Strategy means cutting where the skeleton simplifies most.
True · Balanced branches joined late keep the longest line short.
Swap the group first · Swapping the group can unblock the disconnection.
0.81 · Multiply the step yields: 0.9 times 0.9 is 0.81.
The branched route · Fewer multiplications on the longest line leave more product standing.
The long branch sets the loss · Convergent routes win when branches stay balanced; a seven-step branch drags like a linear route.
Almost no simplification · Strategic bonds are the ones that simplify the skeleton most.