Download Answers to “Tragic Flaws” 1. Can`t form an ether using an alcohol

Answers to “Tragic Flaws”
1. Can’t form an ether using an alcohol with an acid catalyst. Those conditions
would actually protect the aldehyde as an acetal.
2. You want the alcohol to add NON-Markovnikov so you need to use hydroboration,
not acid-catalyzed hydration.
3. Acetals protect aldehydes first, not ketones.
4. The Wolff-Kischner reduction reduces ketones and aldehydes, not alcohols.
Need to oxidize the alcohol first before using the Wolff-Kischner reduction.
5. Similarly to #4, you need to oxidize the alcohol to an aldehyde before doing the
Wittig.
6. TMS-Cl is a protecting group for alcohols, not ketones. Needed to use an acetal.
7. Only diols can be protected as an acetal. Single alcohols cannot. Crashed and
burned on Step 1.
8. Same as #3. But also the use of the Clemmenson would then have knocked off
the acetal shown on the ketone and you would have lost the ketone also.
9. Alcohols protect 1º first, not 2º so the tragic flaw is Step #2.
10. Miscounted the number of carbons atoms in the Wittig reagent. One too many.
11. The methyl group in the Wittig reagent will result in a double bond with the
methyl on the right end of the double bond, not the left, as needed in the
product.
12. (PCC missing from that blank arrow!) Tragic flaw occur in the dehydration
using POCl3 with pyridine – no control over which way the double bond will form
– both sides would form a trisubstituted alkene. Multiple products!
13. Grignard additions form alcohols. Not ketones. Missing an oxidation in the
sequence.
14. Tragic flaws all over the place. Need ketone FIRST to do conjugate addition.
To add ethyl group, need a cuprate, not Et2AlCN. Imine formation must be last
or you won’t have a conjugated ketone to use cuprate with.
15. Oxidize BEFORE using cuprate.
16. The cuprate is written incorrectly, placing the CH3 of the ethyl group as
though it were attached to the Cu – thus putting five bonds on that carbon atom.
Reverse the CH3 and the CH2.