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Synthesis and Reactivity of Sugar Allyltin Derivatives

100%

Jarosz S. , Szewczyk K. , Zawisza A.

Polish Journal of Chemistry

2003

tom Vol. 77 / nr 8

985-994

Thermal stability of primary sugar allyltin derivatives: Sug-CH=CH-CH2SnBu3 was studied. These organometallics with a pyranose ring are stable up to at least 214°C (boiling trichlorobenzene), while those with a furanose ring undergo already at 180°C a controlled decomposition with elimination of the tributylstannyl moiety and opening of the five-membered ring. The mechanism of this process is discussed.

Flash vacuum pyrolysis of 1,3-thiazole-5(4H)-thiones

80%

Leśniak S. , Mlostoń G. , Heimgartner H.

Polish Journal of Chemistry

1998

tom Vol. 72, nr 8

1915-1920

Flash vacuum pyrolysis of 2-phenyl-1,3-oxazol-5(4H)-one (5) at 600degree C/1.5x10(-3) torr proceeded via CO2-elimination to give 3-phenyl-2H-azirine (6) as the only detectable product which was isolated in 34% yield. Under similar conditions, 4,4-dimethyl-1,3-thiazole-5(4H)-thiones 7a and 7b yielded isomeric 1,4,2-dithiazole derivatives 8a,b as main products. Desulfurization leads to 2-(2-propylidene)-1,3-thiazetes 9 as minor products, and in the case of 7a, disulfide 10a is formed as a second minor product.

The Ritter Reaction of Terpenes. Part 3. Investigation of Carvone Related Compounds

80%

Wełniak M.

Polish Journal of Chemistry

2001

tom Vol. 75, nr 1

55-62

The Ritter reaction of (R)-carvone (1), cis-carveol (2) and carvyl ethers 3 and 4 was investigated.For ketone 1 formation of 8-amido-6-p-menthen-2-ones (7-12) in moderate yields was observed. Alcohol 2 gave, depending on the reaction conditions, 2-amido- 6,8(9)-p-menthadienes, 2-amido-4(8),6-p-menthadienes and/or 2,8-diamido-6-p-menthenes. Ethers 3 and 4 underwent cleavage to almost the same amides as it was observed for cis-carveol (2). Additionally, tertiary phenylcarveol (5) under similar conditions furnished 6-acetamido-2-phenyl-1,8(9)-p-menthadiene (28) as a result of dehydration, followed by migration of a double bond. The proposed mechanisms of the reactions are presented.

Structure and Rearrangement of Ring Substituted N0Methyl-N-phenylnitramines

80%

Daszkiewicz Z. , Zaleski J. , Nowakowska E. M. , Kyzioł J. B.

Polish Journal of Chemistry

2002

tom Vol. 76 / nr 8

1113-1125

The mechanism of the acid catalyzed nitramine rearrangement must account for the unusual sensitivity of the reaction of N-methyl-N-phenylnitramine derivatives to the ring substituents. Spectral analyses indicate the lack of interaction between the nitramino group and the second substituent through the aromatic ring. X-ray analyses confirm the spectral data: there is no conjugation between the aromatic and nitramine sextets of _-electrons. X-ray structural data also indicate that the nitramino group cannot behave as the basic centre. A reconsideration of the rearrangement rate constants of the series of ring substituted N-methyl-N-phenylnitramines lead to the conclusion that migration of the N-nitro group precedes protonation. The influence of the substituents on the reaction rates is determined by their influence on the basicity of the imino nitrogen in an intermediate. The CIDNP effect, observed in the rearrangement, results from the transformation of mobile nitrito group into the stable nitro substituent.

Functionalization of the Homoallylic Bridge in Higher Sugar Precursors

80%

Jarosz S. , Szewczyk K. , Gaweł A. , Gomez A. , Lopez J.

Polish Journal of Chemistry

2005

tom Vol. 79 / nr 2

231-238

The Barton reduction of the sugar homoallylic xanthate did not afford the expected hydrocarbon, but led to two cyclic products resulting from the attack of initially formed radical onto the olefin fragment of the homoallylic system. The mechanism of such cyclization is discussed.

Distribution and rearrangement estimates of the maximal function and interpolation

51%

U. Asekritova I. , Krugljak N. Y. , Maligranda L. , Persson L.-E.

Studia Mathematica

1997

tom 124

nr 2

107-132

There are given necessary and sufficient conditions on a measure dμ(x)=w(x)dx under which the key estimates for the distribution and rearrangement of the maximal function due to Riesz, Wiener, Herz and Stein are valid. As a consequence, we obtain the equivalence of the Riesz and Wiener inequalities which seems to be new even for the Lebesgue measure. Our main tools are estimates of the distribution of the averaging function f** and a modified version of the Calderón-Zygmund decomposition. Analogous methods allow us to obtain K-functional formulas in terms of the maximal function for couples of weighted $L_p$-spaces.