Reactions of 4-ethoxy-l,l,l-trifluoro-3-buten-2-one with phosphorous nucleophiles: Diethyl phosphite, tributyl phosphine and tris(diethylamino) phosphine

Abstract The reaction of ( E )-4-ethoxy-l,l,l-trifluoro-3-buten-2-one EtOCH CHCOCF 3 1 with diethyl phosphite (EtO) 2 P(O)H 2 afforded a 1:1 cis - and trans -mixture of diethyl(l-trifluomethyl-3-ethoxy)allyl-phosphate EtO–CH CH–CH(CF 3 )OP(O)(OEt) 2 3 via the 1,2-λ 5 -oxaphosphol-4-ene intermediate. While tributyl phosphine Bu 3 P added to 1 giving the double addition product Bu 3 P + CH 2 –C − (COCF 3 )–CH CH–COCF 3 5 . Its resonance structure was fully identified by spectral methods and single crystal X-ray diffraction analysis. More strong phosphorous nucleophile tris(diethylamino) phosphine (Et 2 N) 3 P reacted with 1 to give the known compound ( E )-4-(diethylamino)-l,l,l-trifluoro-3-buten-2-one Et 2 N–CH CH–COCF 3 10 in good yield.