Three-component coupling of acylphosphonates and two carbonyl compounds promoted by low-valent samariums: one-Pot synthesis of beta-hydroxyphosphonates

Three-component coupling of acylphosphonates and two carbonyl compounds leading to beta-hydroxyphosphonates has been achieved with low-valent samariums. Thus, acylphosphonates reacted with aldehydes in the presence of semicatalytic amounts of samarium metal or SmI(2) to give acyloxyphosphonates in good yields. The second coupling reaction of the acyloxyphosphonates with aldehydes or ketones promoted by SmI(2) afforded beta-hydroxyphosphonates instead of olefins. Moreover, these two reactions could be carried out in one pot.     

Characterization of modified alumina as adsorbents. Modification of alumina with alkali metal phosphates

Summary Alumina may be considerably modified by impregnating at 100°C in the alkali metal phosphate solution. The available solution for modification was the KOH–K₂HPO₄–AlPO₄ (11.51M) solution or the NaOH–Na₂ HPO₄ (0.81.1 M or 11.5M) solution. The appreciable improvement on chromatograms was obtained by preheating of the alumina, especially above 800°C prior to impregnating A further modification may be made by ignition of the alumina impregnated. The x-ray diffraction studies revealed the phase transformation of the alumina inducing the modification, and the essential factor of the present modification method being the thermal treatment of the alumina at temperatures forming -alumina.     

Nonoscillatory solutions of linear differential equations with deviating arguments

Summary The equation to be considered is of the form (1) x(ⁿ)(t)+p(t)x(g(t))=0 (t>a), where =±1, p(t) > 0 for ta and g(t) as t. It is well- known that a nonoscillatory solution x(t) of (1) satisfies (2) x(t)x(ⁱ)(t)>0 (0il), (–1)^i–lx(t)x(ⁱ)(t)>0 (lin) for some integer l, 0ln, (–1)^n–l–1=1. In this paper, for a given l such that 0n–l–1=1, necessary conditions and sufficient conditions are found for (1) to have a solution x(t) which satisfies (2), and a necessary and sufficient condition is established in order that for every >0 the equation x(ⁿ)(t)+p(t)x(g(t))=0 (t>a) has a solution x(t) which satisfies (2). Related results are also contained.     

Synthesis of optically active (+)-19-nortestosterone by asymmetric bis-annulation reaction

Michael reaction of 1,7-pctadien-3-one with 2-methylcyclopentane-1,3-dione, followed by intramolecular aldol condensation promoted by L-amino acids produced the optically active (+)-4-(3-butenyl)-7a-methyl-5,6,7,7a-tetrahydroindane-1,5-dione in high chemical and optical yields. The PdCl₂-catalyzed oxidation of the terminal double bond gave the methyl ketone, which had 76% optical purity and was made 100% optically pure by recrystallization. Then aldol condensation afforded the tricyclic ketone, which was alkylated with 3-butenyl iodide to afford (?)-3β-t-butoxy-2,3,3a,4,5,7,8,9,9aβ,9bα-decahydro-6-(3-butenyl)-3aβ-methyl-1H-benz[e]inden-7-one. The synthesis of this compound means the total synthesis of (+)-19-nortestosterone.     

Infrared spectroscopic study on the reaction mechanism of CO hydrogenation over Pd/CeO2

In situ infrared spectroscopy was applied to elucidate the reaction mechanism of CO hydrogenation over Pd/CeO₂. Instead of direct dissociation of CO, a new reaction pathway is proposed for methane formation, involving geminal dicarbonyl intermediates and (HCO)₂(a) intermediates, which may be located on the surface of Pd covered with thin layers of reduced ceria (SMSI effect). Transformation of methane formation sites into methanol formation ones by the oxidation with water vapor formed during the CO?H₂ reaction is proposed, which may be located on the Pd (111) planes adjacent to ceria support.     

On the photolysis of homo- and copolymers of phenylisopropenylketone

Poly(phenylisopropenylketone (PPIK) and copolymers of PIK and methylmethacrylate (MMA) or styrene (St) were irradiated in benzene solution at 30° with 313 nm light (stationary irradiations) or with 347 nm light (flash photolysis experiments). Homo PPIK undergoes main chain degradation (β-scission) with ø(S) ≈ 0.05. The quantum yield for α-scission is ø(α) = 0.3. For copolymers of MMA and PIK (1 to 15 mol%), ø(S) is 0.04 independent of the copolymer composition. With copolymers of St and PIK, ø(S) was found to increase with decreasing PIK content and to approach 0.15 for very small PIK contents. The flash photolysis experiments showed: (a) the carbonyl triplet decay rate constant k_T(6 × 10⁶ sec^?1) for CP-MMA-PIK samples is independent of copolymer composition but is lower than for homo PPIK (1 × 10⁷ sec^?1). In CP-St-PIK samples k_T decreases with decreasing PIK content [from 8 × 10⁶ sec^?1 (12 mol% PIK) to 3 × 10⁶ sec^?1 (1 mol% PIK)]; (b) the transient spectra of triplet decay products indicate the formation of benzoyl radicals in the cases of PPIK and CP-MMA-PIK, and the formation of various different species in the case of CP-St-PIK.The results are consistent with the following concept. In homo PPIK and CP-MMA-PIK, α-scission (Norrish type I) is the dominant chemical route of triplet deactivation. In CP-St-PIK, however, type II processes become more and more important as the PIK content decreases.     

Skeletal diversity by allylation/RCM on Ugi four-component coupling reaction products

Here, we report a diversity-oriented synthetic approach toward skeletally diverse, cyclized peptidomimetics with diverse appendages. Starting from α-(N-acylamino)amides with various appendages, 12 to 16-membered lactams with defined olefin geometry were synthesized by a common synthetic sequence. We also synthesized the macrocycle in a liquid phase directed toward a construction of the peptidomimetics library.     

Preferential CO oxidation promoted by the presence of H2 over K-Pt/Al2O3

In preferential CO oxidation in H2-rich gas, K-Pt/Al2O3(K/Pt = 10) was very effective in decreasing CO concentration below 10 ppm in the 375-410 K range, and the turnover frequency of the K-Pt/Al2O3 was 20 times as high as that of Pt/Al2O3 at 353 K; furthermore, the activity of CO oxidation was promoted drastically by the presence of H2.     

Radical cyclization in heterocycle synthesis. 11.(1) A novel synthesis of alpha,beta-disubstituted gamma-lactones via sulfanyl radical addition-cyclization using hydroximates as a tether

A combination of sulfanyl radical addition-cyclization of dienes connected with hydroximates and subsequent conversion of the resulting cyclic hydroximate to the lactones provides a novel method for the construction of alpha,beta-disubstituted gamma-lactones. Upon treatment with thiophenol in the presence of AIBN, dienes connected with hydroximates smoothly underwent sulfanyl radical addition-cyclization to give cyclic cis- and trans-hydroximates. Hydrolysis of cyclic hydroximates gave the desired cis- and trans-lactones in high yield. This method was successfully applied to the practical synthesis of (+/-)-oxo-parabenzlactone.     

Development of selective inhibitors against plasma kallikrein.

Specific plasma kallikrein inhibitors were designed and synthesized and their structure-activity relationship was studied. trans-4-Aminomethylcyclohexanecarbonyl (Tra)-lysyl-4-ethoxycarbonylanilide inhibited plasma kallikrein and plasmin with IC50 values of 23 and 210 microM, respectively, indicating that this compound is fairly specific to plasma kallikrein. Tra-arginyl-4-ethoxycarbonylanilide inhibited plasma kallikrein and plasmin with IC50 values of 16 and 480 microM, respectively. Tra-homoarginyl-4-carboxyanilide inhibited plasma kallikrein and plasmin with IC50 values of 14 microM and 1 mM, respectively. Finally, Tra-Arg(Mts)-4-acetylanilide (ACA) exhibited potent and selective inhibitory activity against plasma kallikrein (IC50 value for plasma kallikrein: 2 microM and for plasmin: 42 microM).