Wyniki wyszukiwania - BazTech

1

Functionalization of the Homoallylic Bridge in Higher Sugar Precursors

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

Polish Journal of Chemistry

|

2005

|

Vol. 79 / nr 2

231-238

EN

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.

2

Synthesis and Reactivity of Sugar Allyltin Derivatives

Jarosz S., Szewczyk K., Zawisza A.

Polish Journal of Chemistry

|

2003

|

Vol. 77 / nr 8

985-994

EN

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.

3

Structure and Rearrangement of Ring Substituted N0Methyl-N-phenylnitramines

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

Polish Journal of Chemistry

|

2002

|

Vol. 76 / nr 8

1113-1125

EN

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.

4

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

Wełniak M.

Polish Journal of Chemistry

|

2001

|

Vol. 75, nr 1

55-62

EN

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.

5

Novel A-Hydroxyphosphonates - Enol Phosphates Rearrangement

Wróblewski A., Karolczak W.

Polish Journal of Chemistry

|

1999

|

vol. 73 nr 7

1191-1202

6

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

Leśniak S., Mlostoń G., Heimgartner H.

Polish Journal of Chemistry

|

1998

|

Vol. 72, nr 8

1915-1920

EN

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.