- Co-catalyzed reductive cyclization of azido and cyano substituted α,β-unsaturated esters with NaBH4: enantioselective synthesis of (R)-baclofen and (R)-rolipram
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Sodium borohydride in combination with a catalytic amount of CoCl2 has been found to be an excellent catalytic system in reductive cyclizations of suitably substituted azido and cyano groups of α,β-unsaturated esters to afford γ and δ-lactams in high yields. The process has been demonstrated for the enantioselective synthesis of (R)-baclofen, (R)-rolipram, and (R)-4-fluorophenylpiperidinone, a key intermediate for (-)-paroxetine.
- Paraskar, Abhimanyu S.,Sudalai, Arumugam
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p. 4907 - 4916
(2007/10/03)
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- Metal Exchange between an Electrogenerated Organonickel Species and Zinc Halide: Application to an Electrochemical, Nickel-Catalyzed Reformatsky Reaction
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The mechanism of the electroreductive coupling of α-chloro esters or α-chloro nitriles with carbonyl compounds by the means of a sacrificial zinc anode and a nickel catalyst was elucidated by electroanalytical techniques.The mechanism involved reduction of a Ni(II) complex to a Ni(0) complex, oxidative addition of the α-chloro ester to the Ni(0) complex, and a Zn(II)/Ni(II) exchange, leading to an organozinc Reformatsky reagent.The electrosynthesis of various β-hydroxy esters, β-hydroxy nitriles, and 2,3-epoxy esters was successfully achieved under extremely mild conditions.
- Conan, Annie,Sibille, Soline,Perichon, Jacques
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p. 2018 - 2024
(2007/10/02)
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