Originally posted by Sandmeyer
Quote: | Originally posted by Nicodem
Where did you heard that calcium amalgam reduces conjugated electrophilic double bonds like the sodium amalgam used in the procedure? Aluminium
amalgam is not particularly useful for the reduction of electrophilic double bonds, but if I remember correctly it can do that on some substrates. I
have no idea if it would work on such benzylidenes and besides it would be very, very difficult to work up the reduction due to the acidic phenol
group on this particular substrate. CTH reduction systems, for example HCOOK with Pd/C, can be used to reduce electrophilic benzylidene type double
bonds (as for example in the reduction of cinnamic acids to phenylpropanoic acids). There are a bunch of other CTH systems used specifically for the
reduction of carboxy enamides to amino acid amides, thus suitable to what you want to reduce.
Edit: Any aldehyde without alpha-hydrogens or interfering functional groups can be used instead of vanillin.
[Edited on by Nicodem] |
MeOH/Mg is also effective for this sort of reduction... If someone can get this paper: http://www.ingentaconnect.com/content/ben/coc/2004/00000008/...
Magnesium in Methanol (Mg / MeOH) in Organic Syntheses
Authors: G. H. Lee1; I. K. Youn1; E. B. Choi1; H. K. Lee1; G. H. Yon1; H. C. Yang1; C. S. Pak1
Source: Current Organic Chemistry, Volume 8, Number 13, September 2004, pp. 1263-1287(25)
Abstract:
Magnesium in methanol(Mg / MeOH) system is an extremely versatile, efficient, economical and convenient reducing agent for various reactions useful
for organic synthesis such as reductive cyclization, reductive elimination, reductive cleavage, reduction of a conjugated double bond,
desulfonylation, and reduction of various functional groups. This comprehensive review is intended to highlight the use of Mg / MeOH in each of these
organic transformations. |