RESUMEN
BACKGROUND: In Europe, contact photosensitivity to phenothiazines is well-known, particularly in southern countries. Topical phenothiazines are widely used and sold over-the-counter (OTC) for the treatment of mosquito bites and pruritus in France. OBJECTIVE: To report a series of cases with photodermatitis following use of topical phenothiazines. METHOD: A retrospective study of cases of contact dermatitis from phenothiazines seen in French photodermatology centers was performed. RESULTS: In all, 14 patients with a diagnosis of contact dermatitis from phenothiazines were included. These patients developed eczema on the application sites, and in 13 the eruption spread to photodistributed sites. Topical products containing isothipendyl were the most common cause of photodermatitis. One patient had photoaggravated eczema due to promethazine cream. All patients stopped using topical phenothiazines and were treated successfully with topical corticosteroids. One patient relapsed and developed persistent light eruption. In all of the nine cases tested, photopatch testing to the topical phenothiazine used "as is" was positive. Isothipendyl, chlorproethazine, and the excipients were not tested. Photopatch tests to chlorpromazine and promethazine were positive in 8 of 12 and 7 of 13 tested, respectively. CONCLUSION: Use of isothipendyl and promethazine as OTC (or even prescribed) drugs needs to be limited due to severe reactions and sensitization to other phenothiazines that consequently will have to be avoided.
Asunto(s)
Dermatitis Fotoalérgica/etiología , Fenotiazinas/efectos adversos , Administración Cutánea , Adulto , Anciano , Anciano de 80 o más Años , Clorpromazina/efectos adversos , Clorpromazina/análogos & derivados , Femenino , Antagonistas de los Receptores Histamínicos/efectos adversos , Humanos , Masculino , Persona de Mediana Edad , Prometazina/efectos adversos , Tiazinas/efectos adversosRESUMEN
An approach to 2,4,5-trisubstituted piperidines is reported, in which the key step is the Prins or carbonyl ene cyclisation of aldehydes of the type 1. Prins cyclisation catalysed by concentrated hydrochloric acid in CH(2)Cl(2) at -78 degrees C afforded good yields of two of the four possible diastereomeric piperidines, with the 4,5-cis product 7 predominating in a diastereomeric ratio of up to 94:6. The diastereoselectivity of the cyclisation decreased as the 2-substituent increased in size, becoming unselective for very bulky 2-substituents. In contrast, cyclisation catalysed by MeAlCl(2) in CH(2)Cl(2) or CHCl(3) at temperatures of between 20-60 degrees C, favoured the 4,5-trans diastereomer 8, in a diastereomeric ratio of up to 99:1. The low-temperature cyclisations catalysed by HCl proceed under kinetic control via a mechanism involving the development of significant carbocationic character, in which the 4,5-cis cation is more stable than the 4,5-trans cation as a result of overlap with the neighbouring oxygen. The cyclisations catalysed by MeAlCl(2) proceed under thermodynamic control, affording the product in which both the 4- and 5-substituents are equatorial.
Asunto(s)
Ácido Carbónico/química , Piperidinas/síntesis química , Aldehídos/química , Aminas/química , Aminoácidos/química , Catálisis , Ciclización , Ácido Clorhídrico/química , Estructura Molecular , Nitrilos/química , Ácidos Pipecólicos/química , Piperidinas/química , EstereoisomerismoRESUMEN
2-Methyleneaziridines can be transformed into a variety of 1,3,4,4-tetrasubstituted beta-lactams in moderate to good yields (46-63%) via a "one-pot" process that brings together four components with the formation of three new intermolecular carbon-carbon bonds.
RESUMEN
Cyclisation of aldehydes 3-e catalysed by concentrated hydrochloric acid affords predominantly the all cis 2,4,5-trisubstituted piperidines 4a-ewhen the 2-substituent is small, while catalysis by MeAlCl2 in refluxing chloroform gives the trans piperidines 5a-e with diastereomeric ratios of up to 99:1.