68 research outputs found
The problem of establishing the absolute configuration of the C20-center in steroids of the 17-isopregnane series
Synthesis and reactions of chromium tricarbonyl complexes of 5,10-dihydroindeno[2,1-a]indene
Indenyl and fluorenyl transition metal complexes. VIII. Synthesis, structure and properties of metal carbonyl derivatives of azafluorenes, indole, carbazole and the corresponding anions
The interaction of indole, carbazole and aza-analogues of fluorene, 1-azafluorene (I), 2-azafluorene (II), 3-methyl-II (III), 3-azafluorene (IV), 4-azafluorene (V), 7-methyl-V (VI) and [2,3]benzo-V (VII) with Cr(CO)6 (diglyme/heptane, 140° C), and with (NH3)3Cr(CO)3 (boiling dioxan) and of II with [BrM(CO)5] [NEt4] (M Cr, Mo, W) has been studied. In all cases II and IV form only N-donor complexes of the LCr(CO)5 type, and the other heterocycles: arene-chromium tricarbonyl derivatives coordinated to the benzene, and not the heterocyclic, ring. The interaction of I and III with (NH3)3Cr(CO)3 results in the formation of a mixture of both types of complexes, predominantly arene ones. Reactions with (NH3)3Cr(CO)3 give appreciably higher yields than similar processes involving Cr(CO)6. Deprotonation of arenechromium tricarbonyl compounds (THF, t-BuOK) leads to η6-anions which reversibly isomerize in the case of complexes Ill, V and VI into η5-anions. These are new examples of metallotropic tautomerism in which the metal "slips" between the rings along the plane of the aromatic ligand. In the case of η6-anions of complexes of indole, carbazole, I and VII no such isomerization takes place. Alkylation of η6-anions yields 9-exo-alkyl compounds. These are also the only substances that can be isolated from the alkylation of tautomeric mixtures of anions obtained from XI, XIII and XXIV. © 1982
Indenyl and fluorenyl transition metal complexes. VIII. Synthesis, structure and properties of metal carbonyl derivatives of azafluorenes, indole, carbazole and the corresponding anions
The interaction of indole, carbazole and aza-analogues of fluorene, 1-azafluorene (I), 2-azafluorene (II), 3-methyl-II (III), 3-azafluorene (IV), 4-azafluorene (V), 7-methyl-V (VI) and [2,3]benzo-V (VII) with Cr(CO)6 (diglyme/heptane, 140° C), and with (NH3)3Cr(CO)3 (boiling dioxan) and of II with [BrM(CO)5] [NEt4] (M Cr, Mo, W) has been studied. In all cases II and IV form only N-donor complexes of the LCr(CO)5 type, and the other heterocycles: arene-chromium tricarbonyl derivatives coordinated to the benzene, and not the heterocyclic, ring. The interaction of I and III with (NH3)3Cr(CO)3 results in the formation of a mixture of both types of complexes, predominantly arene ones. Reactions with (NH3)3Cr(CO)3 give appreciably higher yields than similar processes involving Cr(CO)6. Deprotonation of arenechromium tricarbonyl compounds (THF, t-BuOK) leads to η6-anions which reversibly isomerize in the case of complexes Ill, V and VI into η5-anions. These are new examples of metallotropic tautomerism in which the metal "slips" between the rings along the plane of the aromatic ligand. In the case of η6-anions of complexes of indole, carbazole, I and VII no such isomerization takes place. Alkylation of η6-anions yields 9-exo-alkyl compounds. These are also the only substances that can be isolated from the alkylation of tautomeric mixtures of anions obtained from XI, XIII and XXIV. © 1982
Rearrangement of 21,21-dibromo-17?-hydroxypregn-4-ene-3,20-dione into the isomeric 17?, 20?-dihydroxypregn-4-en-21-oic acids
The influence of the configuration of the C-20 substituent in ?4-3-ketones of the pregnane and isopregnane series on the amplitude of circular Dichroism curves
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