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orgo 2 exam 3

Terms in this set (19)

What does LDA do?
Powerful base, product favored, takes alpha H not reversible
How do you get an enol using an alpa hydrogen?
H3O+ (acidic conditions) or OH- (basic conditions)
How do you get a ketone from an alkyne?
Hg2, H2SO4, HOH
How do you get an aldehyde from an alkyne?
1) BH3, THF 2) H2O2, OH-
How do you halogenate the alpha hydrogen?
X2, H+ or OH
How do you halogenate the alpha hydrogen?
X2, H+ or OH
FOr practical aldol how many substrates should have an alpha hydrogen?
Just one
What will decarboxylate and have CO2 as a product?
beta ketoacids
Small hard bases such as grinard (r-mgx) and alkyl lithium (R-Li) add
1,2
Soft bigger bases such as C triple N and LiCuRR add
1,4
A 1,2 addition results in
Nucleophile being added to 2 position and =O being turned into OH
A 1,4 addition results in
Nucleophile being added to the 4 position and =O remaining the same
For an unsymmetric ketone, how do you get alkylation at the more subst alpha C?
Small base, high temp, sl excess of the ketone
For an unsymmetric ketone, how do you get alkylation at the less subst alpha C?
Bulky base, low temp, sl excess of base
What happens if you add X2 in excess and OH- to an alpha hydrogen?
Whole alpha H carbon gets replaced with O-, CHX3 gets formed
For a crossed aldol/claisen schmidt rxn, you want only one reagent to have
alpha H
What does NaOH and heat do? (with something with two =O)
Form a 5 or 6 membered ring
A claisen condesnation results in what?
Two of the same molecule put together with an enolate anion
An aldol reaction results in what?
two of the same together iwth a double bond
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