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Bond energy/eond order relationships for N-O linkages and a quantitative measur...
Johnstone, Robert A. W.; Loureiro, Rui M. S.; Labat, G.; Cristiano, Maria Lurdes SantosThe nitro group is active in metabolic systems and can be found as an integral part of a number of useful curative drugs and many toxic substances. The basis for much of this activity is not fully understood. It is not necessarily caused directly by through-bond electronic effects but may also be due to direct H-bonding to nitro or to indirect interference by the nitro group with existing H-bonding. An unusual ...
Synthesis and structure of novel benzisothiazole-tetrazolyl derivatives for pot...
Frija, Luís M. T.; Fausto, R.; Loureiro, Rui M. S.; Cristiano, M. Lurdes S.http://www.sciencedirect.com/science/article/B6TGM-4V70NKX-1/2/ad205afe2d6f14b54072365e68e443a0
Synthesis and structure of novel benzisothiazole-tetrazolyl derivatives for pot...
Frija, Luís M.T.; Fausto, R.; Loureiro, Rui M.S.; Cristiano, M. Lurdes S.The synthesis and characterization of novel benzisothiazole-tetrazolyl derivatives differing on the spacer-group used for the linkage of two heterocycles are described. The application of these compounds as nitrogen ligands for coordination with transition metals was also explored, leading to the preparation of 3-[1-(2-1H-tetrazol-5-yl)ethoxy]-1,2-benzisothiazole 1,1-dioxide-Mn(II) and N-(1,1-dioxo-1,2-benzisot...
Structural effects on sigmatropic shifts in heteroaromatic allyl ethersElectron...
Araújo, Nuna C.; Barroca, Pedro M. M.; Bickley, Jamie F.; Brigas, Amadeu F.; Cristiano, Maria Lurdes Santos; Johnstone, Robert A. W.In contrast to the known thermal, exclusively [3,3], O- to N- rearrangement of allyl groups in phenyltetrazoles (1, Scheme 1), the comparable migration of the allyl group in pseudosaccharyl ethers (3; Scheme 2) has been shown to proceed through both [1,3]- and [3,3]-mechanisms, 4, 5; for the pseudosaccharyl derivative of the natural product myrtenol (6; Scheme 3) only the product 7 of a [1,3]-shift has been obs...
Thermal rearrangement of 3-allyloxy-1,2-benzisothiazole 1,1-dioxides: an unusua...
Cristiano, Maria Lurdes Santos; Brigas, Amadeu F.; Johnstone, Robert A. W.; Loureiro, Rui M. S.; Pena, Paula C. A.3-Allyloxy-1,2-benzisothiazole 1,1-dioxides isomerize thermally to give [3,3]- and [1,3]-products 6 of sigmatropic shift, of which the former reacts further to give solely the [1,3]-isomer.
3-( E )-But-2-enoxy-1,2-benzisothiazole 1,1-dioxide: unusual C—O—C ether bond l...
Barkley, J. V.; Cristiano, Maria Lurdes Santos; Johnstone, Robert A. W.; Loureiro, Rui M. S.Ethers such as the title compound, C~HIINO3S, (1), rearrange thermally to give N-allyl isomers, (2), in high yield. The X-ray structure determination of the title ether shows a central C--O--C linkage which has one very short (notional) C--O single bond and one exceptionally long single C--O bond. The thermal migration of allyl from the O to the N atom involves the breaking of one of the ether bonds in (1) and ...
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