3.3.3- trifluoropyruvic acid, methyl

HFPO also serves as the starting material for trifluoropyruvic acid derivatives. For example, reaction of HFPO with methanol yields methyl 3,3,3-trifluoro-2-methoxy propionate (XII) that in turn yields methyl trifluoropyruvate (Xni) when treated with antimony pentafluoride. The yields of both these reactions are well over 90% (Eq 13.11). 

Enantioselective Friedel-Crafts alkylation reactions were performed between substituted indoles and methyl trifluoropyruvate, using a chiral nonracemic C2-symmetric 2,2 -bipyridyl copper triflate complex as catalyst. The active copper(II) catalyst was generated in situ. The corresponding 3,3,3-trifluoro-2-hydroxy-2-indolyl-propionic acid methyl esters were formed in good yield (up to 79%), and in up to 90% enantiomeric excess (eq 18). 

Burger2 has shown that alkynes undergo both Lewis acid-catalyzed and thermal carbonyl-yne reactions with 3,3,3-trifluoropyruvates to give allenes. Reaction of 1 (Equation (2)) occurs to give a 1 1 mixture of diastereomeric allenyl carbinols 2. Alternatively, reaction of hexyne 1 and methyl trifluoropyruvate with MgBr2-OEt2 at low temperature afforded 2 as an 8 1 mixture of diastereomers. The thermal reaction does not suffer from allylic alcohol byproducts arising from reaction of the substrate with the Lewis acid.3... 

The acyl imines of methyl trifluoropyruvate react as heterodienes with electron-rich olefins in [4 + 2] cycloadditions, as exemplified by the synthesis of trifluoro-methyl aspartic acid (Figure 5.29). ... 

Pyrimido[4,5-6][l,4]thiazines (262) have been prepared by cyclocondensation of the aminothiols (260) with methyl trifluoropyruvate (261) in benzene (89KGS1492), or with 4-substituted 3-halo-2,4-dioxobutyric acid esters (263) at pH 2-5 in DMF to give 6-carbethoxy-7-acyl derivatives of 5H-pyrimido[4,5-6][l,4]thiazines (264) (Equations (38) and (39)). 

A/ -(Methoxycarbonyl)triphenyl-A -phosphane imidc reacts with methyl trifluoropyruvate to form methyl 3,3.3-trifluoro-2-[(methoxycarbonyl)imino]propanoate (34) in 95% yield. This convenient building block readily undergoes addition of nucleophiles, such as Grignard reagents. without competing side reactions at the ester group to form trifluoromethylated amino acids 35. ... 

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