7b Flashcards
morita baylis hillman recognition
u have an oh, double bond and a carbonyl
on consecutive carbons
how does a morisa baylis hillam reaction occur
u have a nuc (either DABCO or a phsophine nuc - pph3)
this undergoes a conjugate addition reaction and forms an enolate
the enolate attacks an aldehyde // another carbonyl
this carbonyl is protonated to form oh
a beta hydrogen is then removed with a base to form another enolate
this enolate is used to kick off the pph3 // DAPCO original nuc
when we do conjugate addition,, what should we look out for
we need to make sure that the double bond we attack isnt part of an aromatic system
we need to make sure we arent breaking aromaticity.
robinson annulation,, how can we tell this is gonnna occur
one molecule with enolisable protons (aka protons between // near a carbonyl)
one molecule with alkene carbonyl conjugation (where conjugate addition can occur)
steps of a robinson annulation reaction
- base deprotonates a molecule and forms an enolate
- enolate is used as the base for conjugate addition
- enolate formed by conjugate addition attacks H from solvent to saturate the double bond to form an alkane.
- base deprotonates a H to form an enolate (this enolate is gonna be used to attack a carbonyl C so look at ur options)
- enolate attacks carbonyl C
- o- is protonated to give OH
- enolate is formed using base and deprotonation of a H
- OH is eliminated
- alkene and carbonyl are in conjugation.