130973-10-3Relevant academic research and scientific papers
Copper(II)-Catalyzed Reactions of α-Keto Thioesters with Azides via C-C and C-S Bond Cleavages: Synthesis of N-Acylureas and Amides
Maity, Rajib,Naskar, Sandip,Das, Indrajit
, p. 2114 - 2124 (2018/02/23)
Cu(II)-catalyzed reaction of α-keto thioesters with trimethylsilyl azide (TMSN3) proceeds with the transformation of the thioester group into urea through C-C and C-S bond cleavages, constituting a practical and straightforward synthesis of N-acylureas. When diphenyl phosphoryl azide (DPPA) is used instead as the azide source in an aqueous environment, primary amides are formed via substitution of the thioester group. The reactions are proposed to proceed through Curtius rearrangement of the initially formed α-keto acyl azide to generate an acyl isocyanate intermediate, which reacts further with an additional amount of azide or water and rearranges to afford the corresponding products. To demonstrate the potentiality of the method, one-step syntheses of pivaloylurea and isovaleroylurea, displaying anticonvulsant activities, have been carried out.
Synthesis and Catalytic Use of Gold(I) Complexes Containing a Hemilabile Phosphanylferrocene Nitrile Donor
?koch, Karel,Císa?ová, Ivana,?těpni?ka, Petr
supporting information, p. 15998 - 16004 (2015/11/03)
Removal of the chloride ligand from [AuCl(1-κP)] (2) containing a P-monodentate 1′-(diphenylphosphanyl)-1-cyanoferrocene ligand (1), by using silver(I) salts affords cationic complexes of the type [Au(1)]X, which exist either as cyclic dimers [Au(1)]2X2 (3a, X=SbF6; 3 c, X=NTf2) or linear coordination polymers [Au(1)]nXn (3 a′, X=SbF6; 3 b′, X=ClO4), depending on anion X and the isolation procedure. As demonstrated for 3 a′, the polymers can be readily cleaved by the addition of donors, such as Cl-, tetrahydrothiophene (tht) or 1, giving rise to the parent compound 2, [Au(tht)(1-κP)][SbF6] (5 a) or [Au(1-κP)2][SbF6] (4 a), respectively, of which the last two compounds can also be prepared by stepwise replacement of tht in [Au(1-κP)2][SbF6]. The particular combination of a firmly coordinated (phosphane) and a dissociable (nitrile) donor moieties renders complexes 3/3′ attractive for catalysis because they can serve as shelf-stable precursors of coordinatively unsaturated AuI fragments, analogous to those that result from the widely used [Au(PR3)(RCN)]X catalysts. The catalytic properties of the Au-1 complexes were evaluated in model annulation reactions, such as the synthesis of 2,3-dimethylfuran from (Z)-3-methylpent-2-en-4-yn-1-ol and oxidative cyclisation of alkynes with nitriles to produce 2,5-disubstituted 1,3-oxazoles. Of the compounds tested (2, 3 a′, 3 b′, 3 a, 4 a and 5 a), the best results were consistently achieved with dimer 3 c, which has good solubility in organic solvents and only one firmly bound donor at the gold atom. This compound was advantageously used in the key steps of annuloline and rosefuran syntheses.
Total synthesis of siphonazole and its O-methyl derivative, structurally unusual bis-oxazole natural products
Linder, Joerg,Blake, Alexander J.,Moody, Christopher J.
supporting information; experimental part, p. 3908 - 3916 (2009/06/28)
The details of the first syntheses of the unusual bis-oxazole natural products siphonazole and its O-methyl derivative are reported. The cinnamyl substituted oxazole was constructed using diazocarbonyl chemistry, whereby the cinnamamide was reacted with the rhodium carbene derived from methyl 2-diazo-3-oxobutanoate to give a β-ketoamide that was cyclodehydrated to the corresponding oxazole-4-ester. Reduction to the corresponding aldehyde was followed by coupling with a zinc reagent derived from methyl 2-iodomethyl-5-methyloxazole-4-carboxylate, also prepared using rhodium carbene chemistry, to give, after oxidation of the resulting secondary alcohol, the desired bis-oxazole ketone. The syntheses were completed by hydrolysis of the ester and coupling of the 2,4-pentadienylamine side chain. The 2008 Royal Society of Chemistry.
