RESUMEN

PURPOSE: The aim of this work was to retrospectively analyze efficacy, toxicity, and relapse rates of conventional (CRT) and low-dose radiotherapy (LDRT) in patients with indolent orbital lymphomas. PATIENTS AND METHODS: From 1987-2014, 45 patients (median age 64 years) with 52 lesions of indolent orbital lymphomas were treated with CRT (median dose 36 Gy, range 26-46 Gy) and 7 patients (median age 75 years) with 8 lesions were treated with LDRT (2 fractions of  2.0 Gy). RESULTS: Median follow-up was 133 months (range 2-329 months) in the CRT group and 25 months (range 10-41 months) in the LDRT group. Overall response rates were 97.7 % (CRT) and 100 % (LDRT). The 2­ and 5­year local progression-free survival (PFS) rates were 93.5 and 88.6 %, distant PFS 95.0 and 89.9 %, and overall survival 100 and 85.6 % after CRT. In the LDRT group, 2­year local PFS and overall survival remained 100 %, respectively, and distant PFS 68.6 %. Acute radiotherapy-related complications (grades 1-2) were detected in virtually all eyes treated with CRT. Cataracts developed in only patients who were irradiated with more than 34 Gy. LDRT was well tolerated with only mild acute and late complications. CONCLUSION: Primary radiotherapy of indolent orbital lymphomas is an effective treatment with high response rates and excellent local control in CRT and LDRT. In combination with close follow-up, LDRT may be an attractive alternative since re-irradiation even with conventional doses is still feasible.

Asunto(s)

Linfoma/mortalidad , Linfoma/radioterapia , Recurrencia Local de Neoplasia/mortalidad , Recurrencia Local de Neoplasia/prevención & control , Neoplasias Orbitales/mortalidad , Neoplasias Orbitales/radioterapia , Radioterapia Conformacional/mortalidad , Adulto , Anciano , Anciano de 80 o más Años , Supervivencia sin Enfermedad , Relación Dosis-Respuesta en la Radiación , Femenino , Alemania/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Pronóstico , Dosificación Radioterapéutica , Radioterapia Conformacional/estadística & datos numéricos , Estudios Retrospectivos , Factores de Riesgo , Tasa de Supervivencia

RESUMEN

A new generation of alkyne metathesis catalysts, which are distinguished by high activity and an exquisite functional group tolerance, allows the scope of this transformation to be extended beyond its traditional range. They accept substrates that were previously found problematic or unreactive, such as propargyl alcohol derivatives, electron-deficient and electron-rich acetylenes of various types, and even terminal alkynes. Moreover, post-metathetic transformations other than semi-reduction increase the structural portfolio, as witnessed by the synthesis of a annulated phenol derivative via ring-closing alkyne metathesis (RCAM) followed by a transannular gold-catalyzed Conia-ene reaction. Further examples encompass a post-metathetic transannular ketone-alkyne cyclization with formation of a trisubstituted furan, a ruthenium-catalyzed redox isomerization, and a Meyer-Schuster rearrangement/oxa-Michael cascade. These reaction modes fueled model studies toward salicylate macrolides, furanocembranolides, and the cytotoxic macrolides acutiphycin and enigmazole A; moreover, they served as the key design elements of concise total syntheses of dehydrocurvularin (27) and the antibiotic agent A26771B (36).

RESUMEN

Nitride- and alkylidyne complexes of molybdenum endowed with triarylsilanolate ligands are excellent (pre)catalysts for alkyne-metathesis reactions of all sorts, since they combine high activity with an outstanding tolerance toward polar and/or sensitive functional groups. Structural and reactivity data suggest that this promising application profile results from a favorable match between the characteristics of the high-valent molybdenum center and the electronic and steric features of the chosen Ar(3)SiO groups. This interplay ensures a well-balanced level of Lewis acidity at the central atom, which is critical for high activity. Moreover, the bulky silanolates, while disfavoring bimolecular decomposition of the operative alkylidyne unit, do not obstruct substrate binding. In addition, Ar(3)SiO groups have the advantage that they are more stable within the coordination sphere of a high-valent molybdenum center than tert-alkoxides, which commonly served as ancillary ligands in previous generations of alkyne metathesis catalysts. From a practical point of view it is important to note that complexes of the general type [(Ar(3)SiO)(3)Mo≡X] (X = N, CR; R = aryl, alkyl, Ar = aryl) can be rendered air-stable with the aid of 1,10-phenanthroline, 2,2'-bipyridine or derivatives thereof. Although the resulting adducts are themselves catalytically inert, treatment with Lewis acidic additives such as ZnCl(2) or MnCl(2) removes the stabilizing N-donor ligand and gently releases the catalytically active template into the solution. This procedure gives excellent results in alkyne metathesis starting from air-stable and hence user-friendly precursor complexes. The thermal and hydrolytic stability of representative molybdenum alkylidyne and -nitride complexes of this series was investigated and the structure of several decomposition products elucidated.

RESUMEN

Triphenylsilanolate ligands were found to impart excellent reactivity and outstanding functional group tolerance on molybdenum alkylidyne complexes, which catalyze alkyne metathesis reactions of all sorts. The active species either can be obtained in high yield by adaptation of the established synthesis routes leading to Schrock alkylidynes or can be generated in situ from the molybdenum nitride complex 11, which itself is readily accessible in large quantity from inexpensive sodium molybdate. Complexation of the active silanolate complexes 12 and 24 with 1,10-phenanthroline affords complexes 15 and 25, respectively, which are stable in air for extended periods of time. Although these phenathroline adducts are per se unreactive vis-a-vis alkynes, catalytic activity is conveniently restored upon exposure to MnCl(2). Therefore, the practitioner has the choice of different alkyne metathesis (pre)catalysts, which are easy to handle yet broadly applicable and exceedingly tolerant. A host of representative inter- as well as intramolecular alkyne metathesis reactions, including applications to a considerable number of bioactive and, in part, labile natural products, shows the remarkable scope of these new tools. Moreover, it was found that the addition of molecular sieves (5 A >or= 4 A >> 3 A) to the reaction mixture significantly improves the chemical yields while simultaneously increasing the reaction rates. This benefit is ascribed to effective binding of 2-butyne, which is released as the common byproduct in reactions of alkynes bearing a methyl end-cap. Thus, alkyne metatheses can now be performed at ambient temperature with neither the need to apply vacuum to drive the conversion nor recourse to tailor-made substrates. The structures of representative examples of this new generation of alkyne metathesis catalysts in the solid state were determined by X-ray analysis.

RESUMEN

The molybdenum nitride complex [(Ph(3)SiO)(3)Mo[triple bond]N] (10), which can be conveniently prepared in situ from readily available [(Me(3)SiO)(2)((Me(3)Si)(2)N)Mo[triple bond]N] (9) and Ph(3)SiOH, and the pyridine adduct of 10, [(pyridine)(Ph(3)SiO)(3)Mo[triple bond]N] (11), exhibit excellent catalytic activity in alkyne metathesis reactions of all kinds. Adduct 11 is sufficiently stable to be weighed in air and is therefore much easier to use than any of the established, structurally defined alkyne metathesis precatalysts known to date. This new system is compatible with a host of functional groups, including esters, amides, alkenes, carbamates, ethers, silyl ethers, sulfonates, thioethers, THP acetals, glycosides, ketones, enoates, thiophenes, pyridines, thiazoles, and nitro groups, and even accepts protected propargyl alcohols as substrates. It has been used for the preparation of key intermediates for bioactive natural products, such as gallicynoic acid I, homoepilachnene, epothilone A, cruentaren A, and a fully synthetic latrunculin analogue. However, 9 and 11 react with aldehydes and acid chlorides to give the corresponding nitrile derivatives.