ABSTRACT
INTRODUCCIÓN: el linfoma primario del sistema nervioso central (LPSNC) corresponde a una causa de importante mortalidad dentro de los tumores primarios del sistema nervioso central, además existen pocos datos epidemiológicos actualmente, razón por la cual se decide hacer un reporte de casos en el grupo de neuropatología de la Universidad de Antioquia. OBJETIVO: describir el comportamiento de esta patología en un grupo de pacientes. MATERIALES Y MéTODOS: se revisaros los estudios patológicos e historias clínicas de 12 pacientes con diagnóstico de LPSNC en el servicio de neuropatología de la Universidad de Antioquia 2004 el 2011. RESUTADOS: se encontraron 12 pacientes que cumplían el criterio de inclusión. De estos pacientes el 61.5% fueron hombres y el 38.5% mujeres. La edad promedio al momento del diagnóstico fue de 42.6 años (1- 77 años). El Linfoma B no hodking de células gigantes con patrón difuso fue el tumor más frecuente con un 83.3 %, 8.35% corresponde a linfoma de células T, 8.35% a Linfoma de Burkitt; 33.3 % corresponden a pacientes inmunode-ficientes. CONCLUSIóN: en esta serie de pacientes con linfoma del sistema nervioso central se encontraron características clínicas similares a las encontradas en la literatura, quizás el único hallazgo disímil fue la mayor cantidad de pacientes sin aparente alteración en el sistema inmune.
INTRODUCTION: primary lymphoma of the central nervous system (PCNSL) is a major cause of mortality in primary tumors of the central nervous system, plus there are only a few epidemiological data today, these are the reasons why it was decided to make a report of cases in the group of neuropathology at the University of Antioquia. OBJETIVES: to describe the behavior of this disease in group of patients. MATERIALS AND METHODS: we reviewed the pathological studies and clinical records of 12 patients diagnosed with PCNSL in the service of neuropathology at the University of Antioquia from the years of 2004 to 2011. RESULTS: there were 12 patients who met the inclusion criteria. Of these patients, 61.5% were male and 38.5% women. The average age at diagnosis was 42.6 years (1 - 77 years). The giant cell, diffuse pattern B non-Hodgkin lymphoma was the most frequent tumor with 83.3%,T- cell lymphoma with 8.35%, Burkitt lymphoma 8.35%; 33.3% of the patients were immunodeficient. CONCLUSION: in this series of patients with central nervous system lymphoma similar clinical characteristics were found to those in the medical literature, perhaps the only different finding was a higher rate of patients without an apparent alteration in the immune system.
ABSTRACT
The cyclizations of enynes substituted at the alkyne gives products of formal [4+2] cyclization with Au(I) catalysts. 1,8-Dien-3-ynes cyclize by a 5-exo-dig pathway to form hydrindanes. 1,6-Enynes with an aryl ring at the alkyne give 2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes by a 5-exo-dig cyclization followed by a Friedel-Crafts-type ring expansion. A 6-endo-dig cyclization is also observed in some cases as a minor process, although in a few cases, this is the major cyclization pathway. In addition to cationic gold complexes bearing bulky biphenyl phosphines, a gold complex with tris(2,6-di-tert-butylphenyl)phosphite is exceptionally reactive as a catalyst for this reaction. This cyclization can also be carried out very efficiently with heating under microwave irradiation. DFT calculations support a stepwise mechanism for the cycloaddition by the initial formation of an anti-cyclopropyl gold(I)-carbene, followed by its opening to form a carbocation stabilized by a pi interaction with the aryl ring, which undergoes a Friedel-Crafts-type reaction.
ABSTRACT
Three pathways actually compete in metal-catalyzed cyclizations of enynes in which the metal selectively activates the alkyne: an endocyclic process and two exo-cyclizations, one proceeding by anti attack of the alkene and a second one resulting in a syn addition. Although cyclobutenes may be formed in transition-metal-catalyzed cyclization of some enynes, particularly, 1,7-enynes, these compounds are not necessarily the intermediates in the skeletal rearrangement. Cyclobutenes are formed by ring expansion of syn-cyclopropyl metal-carbenes formed in the syn pathway.
Subject(s)
Alkenes/chemical synthesis , Alkynes/chemistry , Transition Elements/chemistry , Alkenes/chemistry , Catalysis , Cyclization , Molecular Conformation , StereoisomerismABSTRACT
Gold(I) complexes are the most active catalysts for alkoxy- or hydroxycyclization and for skeletal rearrangement reactions of 1,6-enynes. Intramolecular alkoxycyclizations also proceed efficiently in the presence of gold(I) catalysts. The first examples of the skeletal rearrangement of enynes by the endocyclic cyclization pathway are also documented. Iron(III) is also able to catalyze exo and endo skeletal rearrangements of 1,6-enynes, although the scope of this transformation is more limited. The gold(I)-catalyzed endocyclic cyclization proceeds by a mechanism different from those followed in the presence of PdII, HgII, or RhI catalysts.
ABSTRACT
Gold(I) complexes are the most active catalysts for the biscyclopropanation of dienynes to form tetracyclic compounds. PtII and ZnII are also able to promote the biscyclopropanation, although less efficiently. The configurations obtained in all cases with the use of gold(I) catalysts can be explained by the pathway proceeding through anti cyclopropyl gold carbenes. Similar intermediates are most probably involved in reactions catalyzed by RuII and PtII. Two different cyclopropanation pathways have been found; they depend on the structures of the cyclopropyl gold carbenes (anti or syn) and the relative arrangements of the metal carbenes and the alkenes.
ABSTRACT
New Au(I) complexes with bulky, biphenyl phosphines are the most reactive catalysts for the cyclizations of enynes. 1,6-Enynes with an aryl ring at the alkyne give 2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes by a 5-exo-dig cyclization followed by a Nazarov-type ring expansion. 1,8-Dien-3-ynes also cyclize by a 5-exo-dig pathway to form hydrindanes.
