An economic and efficient tetrahydrofuranylation of alcohols, imines and alkynes
The tetrahydrofuranyl radical, generated by heating tetrahydrofuran in the presence of air and allyl or benzyl chloride, becomes a useful tool in order to transform the hydroxyl functions into ethers, or the CN double bond into amine, or the C-C triple bond into vinyl derivatives. A radical mechanism is proposed followed by a nucleophilic substitution for the alcohol substrate and a radical addition for the iminic and the acetylenic reactants.
Modelling proposed intermediates in the hydrocarbonylation of alkenes catalysed by rhodium complexes of PBui3 and PPr i3
In ethanol, hydrocarbonylation reactions of alkenes catalysed by triethylphosphine complexes of rhodium give alcohols as the products with low linear selectivity, whilst rhodium complexes of PPri3 or PBui3 give mainly aldehydes, again with low linear selectivity. Modelling the proposed acyl intermediates by studying [Rh(C(O)Me)(CO)m(L)4-m] (L = PPri3 or PBui3) shows that they exist as monophosphine species under the normal reaction conditions. In the absence of CO, [Rh(=C(OH)Me)(CO) L2]+ can also be formed. The implications of these NMR studies for the chemo- and regio-selectivity of the hydrocarbonylation reactions are discussed. The Royal Society of Chemistry.
Cheliatsidou, Paraskevi,White, Daniel F. S.,Slawin, Alexandra M. Z.,Cole-Hamilton, David J.
p. 2389 - 2394
(2008/09/20)
The selective functionalization of saturated hydrocarbons. Part 40. Aspects of Fe(II) based peroxide fragmentation in pyridine solution
The Haber-Weiss mechanism does not apply to the Fe(II) induced fragmentation of primary and secondary hydroperoxides in pyridine. However, it does apply to tertiary hydroperoxides. Steric bulk is an important factor in Fe(II) induced dialkyl peroxide decomposition in pyridine. On the contrary in tetrahydrofuran a different relatively unhindered electron transfer process predominates where the Fe(II) becomes a catalyst.
Barton, Derek H. R.,Launay, Franck
p. 14565 - 14578
(2007/10/03)
Synthesis and Properties of Furan Derivatives 2. Role of the Halogen in RMgX in Reactions with Alkoxytetrahydrofurans
Heating 2-methoxytetrahydrofuran with ethylmagnesium bromide in benzene at reflux leads to the formation of 2-ethoxytetrahydrofuran and slight amounts of 4-methoxy-1-hexanol.Under analogous conditions, 2-ethoxytetrahydrofuran is quantitatively cleaved by
Polivin, Yu. N.,Trofimova, M. V.,Karakhanov, R. A.,Ageev, E. A.
p. 494 - 496
(2007/10/02)
REACTION DES VINYLOGUES D'HEMIACETALS ET DE LEURS EQUIVALENTS SYNTHETIQUES SUR LES ETHERS D'ENOLS HETEROCYCLIQUES
We describe the reaction of hemiacetal vinylogs 2 or their synthetic equivalent with cyclic enol ethers 1 yielding ketoacetals 3.Acidic treatment of these compounds leads to bicyclic heterocycles 8 or enone aldehyde 12 depending on the nature of substituents R1.
Poirier, Jean-Marie,Dujardin, Gilles
p. 3337 - 3340
(2007/10/02)
Studies on the synthesis of chemotherapeutics. I. Synthesis of 1 (2 tetrahydrofuryl) 5 fluorouracil [Ftorafur]. (Studies on the syntheses of heterocyclic compounds. Part 703) (I)
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Kametani,Kigasawa,Hiiragi,et al.
p. 473 - 475
(2007/10/05)
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