Bifunctionalized Allenes. Part Xviii. Synthesis Of 2,5-Dihydro-1,2-Oxaphospholes And 2-Phosphoryl-2,5-Dihydrofurans By Electrophilic Cyclization And Coinage Metal-Catalyzed Cycloisomerization Of Phosphorylated 3-(-Hydroxy) Allenes (Published)
A convenient and efficient regioselective synthesis of phosphorylated 3-(-hydroxy)allenes by an atom economical [2,3]-sigmatropic rearrangement of the mediated propargyl phosphite or phosphinite which can be readily prepared via reaction of protected 1,2,4-triphenyl-1-(tetrahydro-2H-pyran-2-yloxy)-but-3-yn-2-ol with dimethyl chlorophosphite or chlorodiphenyl phosphine respectively is described. This paper discusses a reaction of phosphorylated 3-(-hydroxy)allenes with protected or unprotected hydroxy group involving 5-endo-trig cyclization. Reaction of dimethyl (4-hydroxy-1,3,4-triphenyl-buta-1,2-dienyl)phosphonate with electrophiles that produces 2-oxo-2,5-dihydro-1,2-oxaphospholes due to the participation of the phosphonate neighboring group in the cyclization is described. On the other hand, but-(3E)-en-1-yl phosphine oxides were prepared by chemo-, regio-, and stereoselective electrophilic addition to the C2-C3-double bond in the allene moiety and subsequent concurrent attack of the external (chloride anion) nucleophile. Phosphorylated 3-(-hydroxy)allenes were smoothly converted into the corresponding 2-phosphoryl-2,5-dihydrofurans by using 5 mol % of coinage metal salt as catalyst in 5-endo-trig cycloisomerization reaction.
Keywords: 2, 2-Oxaphospholes, 5-Dihydro-1, 5-Dihydrofurans., Coinage Metal-Catalyzed Cycloisomerization, Electrophilic Cyclization, Phosphorylated 3-(-hydroxy) Allenes