Box Forest Hall No. 2, Newcastle upon Tyne NE12 9TS By using the interaction with p-nitrophenol as a mechanistic probe it has been established that solutions of Nbromo-N-sodiobenzenesulphonamide (bromamine B) in dilute alkali contain two reactive brominating species, the conjugate acid (PhS0,NHBr) and hypobromous acid; formation of the latter can be suppressed by the addition of the parent sulphonamide. These solutions are fully described by a system of four equilibria: three are proton transfer reactions, for which pK, values have been obtained, and the fourth is the alkaline hydrolysis of the conjugate acid, for which an equilibrium constant has been estimated from model experiments with sodium 3 -( N -bromophenylsu1phonamido)propanesulphonate. These data have been used to establish a species distribution diagram and the predictive value of this has been tested.THE chemistry of N-chloro-N-sodiosulphonamides in aqueous solution is reasonably well understood. Recent kinetic studies have established that the reactivity of weakly alkaline solutions of N-chloro-N-sodiotoluene-9-sulphonamide (chloramine T) towards $-cresol,l succinimide,2 and sulphides 3,4 is due to the presence of the conjugate acid, +-MeC,H,SO,NHCl, and/or the disproportionation product, +-MeC,H4S0,NCl, ; hypochlorite was not implicated. Both the dissociation 6 and disproportionation G ~7 constants for N-chlorot oluene-$-sulphonamide have been measured. Surprisingly, almost no information is available on the composition and properties of corresponding solutions of the N-bromo-N-sodiosulphonamides.We are interested in the potential of N-halogenosulphonamide ion as a nucleophile in aqueous solution and have recently described the reactions of the N-chlorospecies with ethylene oxide and propanesultone.8 As essential groundwork for an extension of our nucleophilicity studies to N-bromosulphonamide ion it was decided to investigate the composition of aqueous alkaline solutions of an N-bromo-N-sodiosulphonamide using some convenient organic substrate as a kinetic probe. This work is described in the present paper. EXPERIMENTALReage&.-Reagents used mere of the highest grade commonly available. P-Nitrophenol and toluene-p-sulphonamide were crystallised from toluene and aqueous ethanol (50y0), respectively, before use. Bromamine B (1) was prepared from the sulphonamide, bromine, and aqueous sodium hydroxide by a published p r o c e d ~r e . ~ Repeated recrystallisation from dilute aqueous sodium hydroxide (10-3~) and drying in VUGUO (P,O,) gave the sesquihydrate (Found:

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A POSSIBLE biosynthetic relationship between the atisine to a 7-5 B/C ring system; (b) formation of the C-7 -+ C-20 and aconitine-lycoctonine groups of diterpene alkaloids bond by Mannich addition. The order of steps (a) and (b) was sug5ested independently by Valenta and Wiesnerl and might be reversed. A re-e~aluation~,~ of the mechanism by Cool:son and Trevett in 1956.2 In essence, both schemes which generates the well-known "pyro" compounds in the consist of the two steps depicted in (I) -+ (11) : (a) Wagner-aconitine series, suggests a modification of the original ;\leerwe in rearrangement of a C,, (loss of C-17 of atisine) Wiesner-Cookson hypothesis. -4ccording to this, the interintermediate (I) derivable from atisine, leading from a 6-6 mediate alkene (111) participates in a Prins-type addition

Aus Atisin (I) werden über die entsprechenden Hydroxyketone das Tosylat (II) und sein α‐Isomeres erhalten.