64985-90-6Relevant academic research and scientific papers
Organomolybdenum and Organotungsten Reagents, V. - On the Additive, Reductive Carbonyl Dimerization (ARCD Reaction)
Kauffmann, Thomas,Jordan, Jan,Voss, Karl-Uwe,Wilde, Heinz-Wilhelm
, p. 2083 - 2092 (2007/10/02)
Reagents of the type R4(PrO)4(μ-PrO)2W2 (3; R = Me, Et, Pr, Bu, sBu, iBu, Hex, Me3SiCH2, Ph) prepared in situ by the action of organolithium or Grignard compounds on (PrO)4(μ-PrO)2W2Cl4 (2), react with aromatic aldehydes or ketones and with the α,β-unsaturated ketone benzylidene acetone in a novel reaction, called the ARCD reaction, to give products 4 of the type RR'R''C-CRR'R'' with mostly good yields.In the case of benzylidene acetone and furfural besides the ARCD products the rearranged products 27 and 29 are formed.With the reagent Ph4(PrO)4(μ-PrO)2W2 (3b) ARCD reactions are also possible in moderate yields with aliphatic aldehydes and ketones.The more closely investigated reagent Me4(PrO)4(μ-PrO)2W2 (3a; decomposition at about -45 deg C) tolerates the aromatic bound functional groups Cl, F, OH, OMe, and NMe2 in the substrates, but not the NO2 and CO2Et substituents.It reacts with PhCOX (X = OEt, Cl, OCOPh) via acetophenone to give PhCMe2-CMe2Ph. - For the ARCD reactions a radical mechanism (Scheme 7) is postulated. - Key Words: Tungsten complexes/ Carbonyl dimerization
Reaction of Organic Halides with Chlorotris(triphenylphosphine)cobalt(I)
Momose, Den-ichi,Iguchi, Kazuo,Sugiyama, Toshikazu,Yamada, Yasuji
, p. 1840 - 1853 (2007/10/02)
Reaction of various types of organic halides with a monovalent cobalt complex, chlorotris(triphenylphosphine)cobalt(I) is described.Reaction of benzylic monohalides, dihalides and trihalides with CoCl(Ph3P)3 gave a coupling product with formation of a carbon-carbon single bond, double bond and triple bond, respectively, under mild and non-basic conditions.Dehalogenation of non-benzylic vicinal dihalides with the reagent took place cleanly to give an olefin in high yield.Reductive coupling of allylic halides using the reagent afforded regioselectively a 1,5-diene with retention of the stereochemistry of the carbon-carbon double bond of the allylic halides used.By using this reaction, (E,E,E,E)-squalene was stereospecifically synthesized from (E,E)-farnesyl bromide.Reaction of halohydrins with CoCl(Ph3P)3 gave exclusively a ketone in the presence of an amine or olefin through an alkylcobalt intermediate.A 1,2-hydrogen shift is involved in this reaction.Keywords - chlorotris(triphenylphosphine)cobalt(I); coupling reaction; benzylic halides; allylic halides; synthesis of 1,5-diene; squalene; halohydrin; ketone synthesis.
REDUCTIVE COUPLING OF BENZYLIC HALIDES BY CHLOROTRIS(TRIPHENYLPHOSPHINE)COBALT(I)
Yamada, Yasuji,Momose, Den-ichi
, p. 1277 - 1278 (2007/10/02)
Chlorotris(triphenylphosphine)cobalt(I) is an effective agent for the reductive coupling of benzylic halides under mild and neutral conditions.
