- HIGH YIELD ACYL ANION TRANSFER REACTIONS: NUCLEOPHILIC ACYLATION OF ALDEHYDES
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Aldehydes be may acylated to give R'CH(OH)C(O)R in good yield by the RLi/CO in situ procedure at very low temperatures.Examples are given of ketone acylations which demonstrate the advantages of 1:1 RLi/substrate stoichiometry and the use of lower (-135 deg C) temperature.
- Seyferth, Dietmar,Weinstein, Robert M.,Wang, Wei-Liang,Hui, Richard C.
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- Imidoyl chlorides as starting materials for the preparation of masked acyllithium intermediates: Synthetic applications
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The lithiation of several imidoyl chlorides 5, catalysed by substoichiometric amounts of naphthalene, followed by reaction with different electrophiles gives, after hydrolysis, the corresponding imine derivatives 6 and 9 or amines 7, depending on the reac
- Alonso, Emma,Ramon, Diego J.,Yus, Miguel
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p. 12007 - 12028
(2007/10/03)
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- Imidoyllithiums: Masked acyllithium reagents
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The reaction of chloroimines 1 with an excess of lithium powder and a catalytic amount of naphthalene (4 mol %) in THF at -78°C leads to the corresponding imidoyllithium intermediates 2, which by treatment with different electrophiles [PriCHO, Bu(t)CHO, n-C5H11CHO, PhCHO, Et2CO, (CH2)5CO, EtOCOCl, MeOCSCl, n-C7H15CON(Me)OMe] at -78 to 20°C and final hydrolysis with water affords functionalysed imines 3. For starting material la is necessary to filter off the excess of lithium at the end of the lithiation step in order to get compounds 3, without filtration amines 4 are the reaction products isolated. Hydrolysis of compounds 3 either during chromatographic purification or by acidic hydrolysis (2 N HCl, THF) gives the expected functionalised ketones 5.
- Alonso, Emma,Ramon, Diego J.,Miguel, Yus
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p. 8903 - 8906
(2007/10/03)
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- Synthesis of α-Hydroxy Ketones by Direct, Low-Temperature, in Situ Nucleophilic Acylation of Aldehydes and Ketones by Acyllithium Reagents
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The reaction of n-, sec-, and tert-butyllithium with CO at atmospheric pressure at -110 and -135 deg C in the appropriate solvent system in the presence of ketones and aldehydes generates the acyllithium, RC(O)Li, which reacts with the carbonyl compound to give the α-hydroxy ketone, generally in good yield.Reactions with aldehydes are limited in scope, working well with the t-BuLi-derived acyllithium reagents, but not with n-BuC(O)Li.
- Seyferth, Dietmar,Weinstein, Robert M.,Hui, Richard C.,Wang, Wei-Liang,Archer, Colin M.
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p. 5620 - 5629
(2007/10/02)
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