Methyl trifluoropyruvate preparation

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 convenient two-step methodology for the preparation of 4-trifluoromethyl-(2//)-pyridazin-3-ones starting from methyl trifluoropyruvate MeTFP (1015) was developed (Scheme 216) [612], The approach relied on aldol condensation of 1015 with various ketones, followed by reaction of the adducts 1016 with hydrazine. Recently, this methodology was used for the preparation of y-secretase modulators [613],... 

Bravo et al. treated (Ss)-(+)-p-toluenesulfinamide (63), prepared by hydrolysis of 44,23 with triphenylphosphine in the presence of DEAD to give the N-sulfinyl iminophosphorane 64 in 92% yield.45 The Staudinger, aza-Wittig reaction of 64 with methyl or ethyl trifluoropyruvate afforded the unstable sulfinimine 65. Attempts to purify the imino sulfinimines by flash chromatography resulted in hydrolysis. 

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