Zobrazeno 1 - 10
of 161
pro vyhledávání: '"A S, Campos Neves"'
Publikováno v:
Tetrahedron Letters. 40:8711-8714
Ultrasonic irradiation of bromohydrins in the presence of (diacetoxyiodo)benzene and I 2 generates alkoxyl radicals which lead in situ to intramolecular hydrogen abstraction on the C-19 non-activated carbon atoms in steroids producing tetrahydrofuran
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::76eee130a5ca6e130b7c79370f446d84
https://doi.org/10.1016/s0040-4039(99)01849-3
https://doi.org/10.1016/s0040-4039(99)01849-3
Autor:
Maria José S. M. Moreno, Saul P. da Costa, André S. Campos Neves, R. M. L. M. Martins, Maria Luisa Sá e Melo
Publikováno v:
Tetrahedron. 54:13877-13886
21-Hydroxylation and acetoxylation of 20-oxosteroids, either α,β-unsaturated or β-substituted, were successfully achieved through oxidation of the corresponding silyl enol ethers with m -CPBA followed by smooth hydrolytic cleavage of the 21-alkyls
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::88835ed782d25b598c135bc984613eba
https://doi.org/10.1016/s0040-4020(98)00854-0
https://doi.org/10.1016/s0040-4020(98)00854-0
Autor:
José A. Paixão, Elisiário J. Tavares da Silva, Maria Luisa Sá e Melo, Maria-José M. Almeida, L. C. R. Andrade, M. M. R. R. Costa, André S. Campos Neves
Publikováno v:
Journal of the Chemical Society, Perkin Transactions 1. :3487-3490
A convenient synthetic strategy for the preparation of ring-D lactones of the androstane derivatives 4, 5 and 6 has been achieved through a high yielding, three-step sequence. Baeyer–Villiger oxidation of 3α,4β-dihydroxy-5α-androstan-17-one 3, p
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::1187a2728b40078138f46ad80adb5226
https://doi.org/10.1039/a705601j
https://doi.org/10.1039/a705601j
Publikováno v:
Tetrahedron Letters. 38:119-122
Δ5-7-Oxosteroids are efficiently prepared from Δ5-steroids with t-BuOOH and a copper catalyst, either Cu(II) and Cu (I) salts or Cu metal; selectivity in the presence of a secondary alcohol is observed.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::86af0d5a7e753e284408a1fd1b843433
https://doi.org/10.1016/s0040-4039(96)02231-9
https://doi.org/10.1016/s0040-4039(96)02231-9
Publikováno v:
Tetrahedron Letters. 37:687-690
The β-epoxidation of 3 β -acetoxy-Δ 5 -unsaturated steroids has been achieved with mmerous potassium permanganate-metal sulphates and nitrates with a high degree of stereoselectivity. 5β,6β-Epoxides are formed in a one step reaction in good yiel
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::20a1111f850c9b52623cb29583b2477a
https://doi.org/10.1016/0040-4039(95)02243-0
https://doi.org/10.1016/0040-4039(95)02243-0
Autor:
H. I. M. Soares, M. J. M. de Almeida, M. J. S. M. Moreno, A. S. Campos Neves, José A. Paixão, M. L. Sa E Melo, L. C. R. Andrade, R. M. L. M. Martins
Publikováno v:
Acta Crystallographica Section E Structure Reports Online. 59:o299-o301
The title compound, C25H34O6, has a 3β,21-configuration, with the epoxy O atom at 16α,17α. Rings A and C have chair conformations which are slightly flattened. Because of the presence of a double bond, ring B assumes an 8β,9α-half chair conforma
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::d885b573a51b52b85a8ff7bf63f47358
https://doi.org/10.1107/s1600536803002721
https://doi.org/10.1107/s1600536803002721
Autor:
José A. Paixão, M. L. Sa E Melo, Fernanda M.F. Roleira, L. C. R. Andrade, E. J. Tavares da Silva, A. S. Campos Neves, M. J. M. de Almeida
Publikováno v:
Acta Crystallographica Section E Structure Reports Online. 59:o21-o23
The ring conformation of the title compound, C19H30O3, is similar to that of the 5α-epimer except for the cis A/B ring junction. Ring D adopts a 13β,14α-half chair conformation. The molecules are linked together by a two-dimensional network of h
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::91ff2cb469b60873307ebf5ce5979655
https://doi.org/10.1107/s1600536802022055
https://doi.org/10.1107/s1600536802022055
Autor:
José A. Paixão, M. M. Cruz Silva, M. J. M. de Almeida, M. J. S. M. Moreno, M. L. Sa E Melo, A. S. Campos Neves, L. C. R. Andrade
Publikováno v:
Acta Crystallographica Section E Structure Reports Online. 58:o898-o900
The title compound, C25H36O5, has two independent molecules in the asymmetric unit with similar geometry. The main difference between the two molecules relates to the conformation of the 17β-methyl ketone and 3β-acetoxy groups, the latter being
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::e7d60a4ecb9713a09de68ac326db8974
https://doi.org/10.1107/s1600536802012862
https://doi.org/10.1107/s1600536802012862
Publikováno v:
Tetrahedron Letters. 34:357-360
Zinc reduction of α, β-unsaturated ketones in acetic acid has been efficiently accomplished under sonochemical conditions. Different α-enone systems give two kinds of products: olefins and allylic alcohols. Regio- and stereoselective are reported.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::744c21660e18a359d841acabde017961
https://doi.org/10.1016/s0040-4039(00)60587-7
https://doi.org/10.1016/s0040-4039(00)60587-7
Publikováno v:
Tetrahedron Letters. 34:353-356
The sonochemical reductive opening of α, β-epoxy ketones and their α′-oxygenated (-OH or -OAc) analogs by aluminium amalgam allows shorter reaction times, better yields of the respective β-hydroxy ketones and minimization of by-products. The ra
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::41f8ca05b32a83e5f0371e1dbf7a3ae8
https://doi.org/10.1016/s0040-4039(00)60586-5
https://doi.org/10.1016/s0040-4039(00)60586-5