Trimethyl orthoformate

Trimethyl orthoformate is the simplest orthoester.  It is a reagent used in organic synthesis for the introduction of a protecting group for aldehydes. The product of reaction of an aldehyde with trimethyl orthoformate is an acetal. In general cases, these acetals can be deprotected back to the aldehyde by using hydrochloric acid.

The industrial synthesis of this chemical is from hydrogen cyanide and methanol.

Trimethyl orthoformate is a useful building block for creating methoxymethylene groups and heterocyclic ring systems. It introduces a formyl group to a nucleophilic substrate, e.g. RNH2 to form R-NH-CHO, which can undergo further reactions. It is used in the production of the fungicides, azoxystrobin and picoxystrobin, as well as for some members of the floxacin family of antibacterial drugs. 
A number of pharmaceutical intermediates are also made from trimethyl orthoformate.
Trimethyl orthoformate (TMOF) is an excellent reagent for the conversion of compatible carboxylic acids to the corresponding methyl esters. Refluxing such acids with excess neat TMOF until low-boilers cease evolution provides quantitative conversion to methyl esters, without need for catalysis.  Ref. J.B. Paine III, J. Org. Chem. 2008, 73, 4929-4938.  Alternatively, acid-catalyzed esterifications with methanol can be driven closer to completion by employing TMOF to convert water byproduct to methanol and methyl formate.

Preparation
Trimethyl orthoformate can also be prepared from the reaction between chloroform and sodium methoxide, an example of the Williamson ether synthesis.

See also
Pinner reaction

References

Category:Reagents for organic chemistry
Category:Orthoesters
Category:Methyl esters