138924-75-1Relevant academic research and scientific papers
Reactions between Tantalum- or Niobium-Alkyne Complexes and Carbonyl Compounds
Kataoka, Yasutaka,Miyai, Jiro,Oshima, Koichiro,Takai, Kazuhiko,Utimoto, Kiitiro
, p. 1973 - 1981 (2007/10/02)
A variety of tantalum-alkyne complexes are generated in situ by treatment of alkynes with low-valent tantalum derived from TaCl5 and zinc.These complexes add regioselectively to carbonyl compounds in a one-to-one fashion to yield (E)-allylic alcohols stereoselectively.Iodinolysis of the oxatantalacyclopentene, which is postulated as an intermediate of the reaction, gives a (Z)-3-iodo-2-propen-1-ol derivative.In contrast to tantalum-alkyne complexes, niobium-alkyne complexes, prepared with low-valent niobium derived from NbCl5 and zinc, add in situ to aldehydes in a one-to-two fashion to give 1,3-diene derivatives.The dienes are produced through (i) addition of the alkyne complexes with 2 equiv of aldehydes at cis vicinal positions of the alkenes and (ii) deoxygenative elimination of 2,7-dioxanioba-4-cycloheptene complexes.
