The mass spectra of nineteen substituted benzothiazoles have been recorded and the identity of the various ions in the mass spectra has been established by high resolution (accurate) mass measurement. Deuterium labelling has been used to elucidate the fragmentation processes of these compounds. The parent compound of the series, benzothiazole, exhibits the loss of hydrogen cyanide and carbon monosulphide from the parent ion as the most important decomposition pathways, The hydrogen atom concerned in the loss of hydrogen cyanide is shown to originate from the 2-position of benzothiazole, while in 2-substituted benzothiazoles, different mechanisms are apparent for the loss of hydrogen cyanide, and these are clarified by deuterium labelling. Some substituted benzothiazoles can lose sulphur from their molecular ions, a process which does not occur in benzothiazole itself. The substituted benzothiazoles undergo many other types of fragmentations, in some cases retaining the substituent, and in other cases losing it prior to collapse of the thiazole ring.

The Synthesis of Indenoquinolines. 207 36.The Synthesis of Indenoquinolines.

Abstract-Although the behaviour of 1 H, 2H-2,1,3-benzothiadiazoline 2,2-dioxide is similar to that of sulphoxides in the mass spectrometer in losing a molecule of SO2, the 1,3-dimethyl derivative loses the radical S02H. In addition the radical CH,SO, is lost in a one step process that must involve a methyl migration. The radical S02H is also lost from 2,1,3-benzothiadiazine 2,2-dioxides methylated in the 3-position and the hydrogen involved is shown to originate from this methyl group by deuterium labelling. The mass spectra of other 2,1,3-benzothiadiazine 2,2-dioxides are also discussed.

The preparation of 7‐amino‐2,3‐dihydro‐8‐nitro‐1H‐pyrrolo[1,2‐a]benzimidazole from 1,4‐diacetamido‐2,3‐dinitrobenzene is described. Reaction of this compound with 2,5‐dimethoxytetrahydrofuran produces 2,3‐dihydro‐8‐nitro‐7‐N‐pyrrolo‐1H‐pyrrolo[1,2‐a]benzimidazole, which can be cyclised to produce two new heterocyclic ring systems, 9,10‐dihydro‐8H‐pyrrolo[1,2‐a]pyrrolo(1′,2′:1,2]imidazo[5,4‐f]quinoxaline and 9,10‐dihydro‐8H‐pyrrolo[2,1‐c]pyrrolo[1′,2′:1,2]imidazo[4,5‐h][1,2,4]benzotriazine. The corresponding diamine, 7,8‐diamino‐2,3‐dihydro‐1H‐pyrrolo[1,2‐a]benzimidazole undergoes a variety of condensation reactions to produce several new heterocyclic systems, for example, with formic acid, 1,7,8,9‐tetrahydroimidazo‐[4,5‐e]pyrrolo[2,1‐6]benzimidazole is formed and with diacetyl, 9,10‐dihydro‐2,3‐dimethyl‐8H‐pyrrolo‐[1′,2′:1,2]imidazo[5,4‐y]quinoxaline is obtained.

Reaction of phenacetyl chlorides with alkyl or DERIVATIVES of isoquinolin-3-01 have previously been prearyl thiocyanates in the presence of a Friedel-Crafts pared by the cyclisation of o-acylphenylacetic acids with catalyst yieIds 1-substituted-isoquinolin-3-01s.ammonia or amines,l the acid-catalysed cyclisation of