Umsetzung von Di(tert‐butyl)‐ und Diphenyldiazomethan mit 1,3‐Thiazol‐5(4H)‐thionen: Isolierung und Kristallstruktur des primären Cycloadduktes

摘要: Reaction of Di(tert-butyl)- and Diphenyldiazomethane 1,3-Thiazole-5(4H)-thiones: Isolation Crystal Structure the Primary Cycloadduct Reactions diazo compounds with CS bonds proceed via formation thiocarbonyl ylides, which, under reaction conditions, undergo either 1,3-dipolar cycloadditions or electrocyclic ring closer to thiiranes (Scheme 1). With sterically hindered di(tert-butyl)diazomethane (2c), 1,3-thiazole-5(4H)-thiones 1 react give spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3 2). These adducts are stable in solution at −20°, they could be isolated crystalline form. The structure 3c was established by X-ray crystallography. In CDCl3 room temperature, a cycloreversion occurs, type an equilibrium 2c. contrast, diphenyldiazomethane (2d) gave 4 as only product high yield 3). crystal 4b also determined analysis. desulfurization 4,5-dihydro-5-(diphenylmethylidene)-1,3-thiazoles 5 achieved treating triphenylphosphine boiling THF. 5f is shown.