The course of the reactions o f fluorophosphaalkenes F3CP = C (F)OR [R = Me (1), Et (2)] with methanol or ethanol strongly depends on the experimental conditions. Thus at 70 °C a mixture of the 2-phosphapropionic acid ester F3CP (H )CO2R [R = Me (3), Et (4)] and trifluoromethylphosphane H2PCF3 is formed [molar ratio: 3 or 4 /H2 CF3 ≈1/1]. If the precursors F3CP (H )CO2R [R = Me (3), Et) are used as starting materials, the reaction with ROH under the same conditions affords 3 and 4, respectively, (90 to 95% yield) with only traces of H2PCF 3. In the presence o f iPr2NH these precursors react with R′OH to give the novel trifluoromethylphosphaalkenes F3CP = C (OR )OR [R /R′: Me/Me (6); E t/E t (7); Me/Et (8)]. With Et2NH , 3 undergoes an addition/elimination process yielding the interesting push/pull system Et2N(F)C = P-CO2Me (5). 1 and 2 react with primary amines R′NH2 (R′= tBu, Me) with stereoselective formation of the fairly labile phosphaalkenes F3CP = C(OR)NHR′ [R /R′: Me/tBu (9), Et/tBu(10), Me/Me (11)] with trans-positions for CF3 and NHR′.The new compounds 3 -11 were characterized by spectroscopic investigations (1H , 19F, 31P, 13C NMR ; IR, MS) and determination of M+ or typical fragment ions [M+ -OR ] by high resolution mass spectrometry.