Regioselective hydration of alkynones by palladium catalysis
作者:Katsuharu Imi、Kumiko Imai、Kiitiro Utimoto
DOI:10.1016/s0040-4039(00)96302-0
日期:1987.1
Diketones are regioselectively prepared from alkynyl ketones under mild conditions by palladium catalysis; 5-heptyn-2-one and 2-(2-nonynyl)cyclohexanone give 1,4-dikektones whereas 2-(2-heptynyl)cyclopentanone and 5,6-didehydroprostaglandin E2 methyl ester afford 1,5-diketones.
New effective catalysts for Mukaiyama-aldol and -Michael reactions: bismuth trichloride-metallic iodide systems
作者:Christophe Le Roux、Hafida Gaspard-Iloughmane、Jacques Dubac、Joel Jaud、Pierre Vignaux
DOI:10.1021/jo00059a040
日期:1993.3
Metallic iodide-activated bismuth(III) chloride efficiently catalyzes the Mukaiyama-Aldol and -Michael reactions. Some examples of reactions of silyl enol ethers derived from acetophenone and cyclohexanone (I and 2, respectively) with aldehydes, ketones, acetals, and alpha-enones are given. The cross-over aldolization between 1 and benzaldehyde in the presence of BiCl3-l.5ZnI2 or BiCl3-1.5SnI2 systems (5 % mol) has been carried out quantitatively at -30 and -78-degrees-C, respectively. For this reaction a similar activation has been also observed with antimony(III) chloride. X-ray patterns of catalytic systems show the formation of bismuth(III) iodide by CI/I-exchange reaction between BiCl3 and metallic iodide (NaI, ZnI2, SnI2,...). These results.have been rationalized with a two-step mechanism in which a key feature seems to be the activating role played by BiI3 toward the cleavage of the Bi-chelate intermediate by the chlorosilane formed. Ultrasound activates significantly the catalytic power of these metallic halide systems.
Ranu, Brindaban C.; Saha, Manika; Bhar, Sanjay, Journal of the Chemical Society. Perkin transactions I, 1994, # 15, p. 2197 - 2200
作者:Ranu, Brindaban C.、Saha, Manika、Bhar, Sanjay
DOI:——
日期:——
Organotin triflates as functional lewis acids. A new entry to simple and efficient robinson annulation