Introduction
N,N-Dimethylformamide dimethyl acetal
(DMF·DMA), as well as other N,N-dimethylfomamide
dialkyl acetals (e.g. ethyl, benyzl, t-butyl),
are very useful reagents in organic synthesis. All of them are used
in two main categories of reactions, namely alkylation and formylation.
The mechanism of these reactions probably includes generation of
an oxo-stabilized carbenium ion.
[1]
[2]
As alkylating agents they have been used in the synthesis of
esters from acids, ethers from phenols, and thioethers from aromatic
and heterocyclic thiols. As formylating agents, formamide acetals
are useful in the synthesis of enaminones from active methylene
compounds and amidines from amines and amides. These compounds are found
to be useful intermediates in the formation and modification of
many heterocyclic
[1]
and biologically
active compounds.
[3]
The N,N-dibenzyl formamidine group
was also found to be effective as a protecting group for primary
amines. It is stable under variety of conditions and can be removed
by catalytic hydrogenation.
[4]
All
conversions proceed under mild conditions and in high yields.
Many formamide acetals are comercially available. In addition,
they can be prepared by addition of chloroform into a refluxing
solution of sodium alkoxide in the appropriate alcohol and the secondary
amine.
[5]
