Exam 2 Flashcards
(23 cards)
Reduces Dithioacetals, alkenes, and nitro groups to the alkane oxidation state
Raney Nickel, EtOH
Oxidizes a primary alcohol to an aldehyde and a secondary alcohol to a ketone
PCC, CH2Cl2
Oxidizes primary alcohol to carboxylic acid and secondary alcohol to ketone
Jones’ Reagent
What should you do if there are two heteroatoms attached to the same carbon and one is positively charged?
use the lone pairs on the other atom to eject the positive one
What is the pattern observed when there is a heteroatom attached to a double bond (enol ether) and we are adding an electrophile?
electrophile or proton adds to the carbon of the double bond furthest from the heteroatom
Deprotects dithioacetals to give ketone or aldehyde
HgCl2, CaCo3, THF/H2O
What will happen if there is a ketone or aldehyde that is 5 or 6 atoms apart from an OH? Which conditions does this take place in?
Intramolecular cyclization. Can happen in acidic OR basic conditions
Reagents for THP protecting group?
DHP, H+ Cat, CH2Cl2
Reagents for dithioacetal protecting group
HS(CH2)3SH, BF3, CH2Cl2
what is the difference b/w a stabilized and destabilized ylide?
There is an EWG on the carbon adjacent to the neg. chg. Stabilized gives exclusively trans product. Cis is the major pdt of unstabilized ylide.
Why can’t you have an oxygen group such as OTBS adjacent to the ylide?
E1CB elimination
Reagents for acetal formation?
HO(CH2)2OH, H+ cat, toluene, (-H2O), delta
What do these reagents do: NH2NH2, KOH
reduces aldehydes and ketones to the alkane
How would you move an aldehyde over 1 carbon?
Homologation - OMe ylide then H30+, delta
What is the difference b/w an imine and an enamine?
Enamine comes from a secondary amine and requires removing a H from the carbon adjacent to the carbon the N atom is on
we don’t make which kind of intermediates in acidic conditions? Which one do we not make in basic conditions?
alkoxides (neg. charge int.) ; carbocations, oxonium ions
What must we do when we want to make a Grignard but an OH, ketone, or aldehyde is present?
Protect them first
We can not do an E2 like mechanism unless we have…
a strong base(alkoxide)
Why does Jones’ reagent lead to the carboxylic acid in a primary alcohol?
bc H30+ is present and the aldehyde is in equilibrium with the 1,1-diol
Reduces aldehydes and ketones to the alcohol
a) NaBH4, MeOH b)H3O+ workup
Write the mechanism for imine formation backwards and forwards for acetone
X
Write the mechanism for dithioacetal formation forwards and backwards for acetone
X
Write the mechanism for Jones’ Reagent oxidation for a primary alcohol
X
