Articles written in Proceedings – Section A
Volume 36 Issue 5 November 1952 pp 405-410
5-Bromothionaphthene and 7-bromothionaphthene were prepared by the cyclization of
The new synthesis of thionaphthene may also be extended to negatively substituted thionaphthenes as shown by the synthesis of 5-nitrothionaphthene (VI) by the ring-closure of
Volume 36 Issue 5 November 1952 pp 411-418
A new synthesis of dibenzothiophene (I) which has been extended to its substituted derivatives has been developed. It consists in the condensation of thiophenol with 2-bromocyclohexanone to give 2-phenylmercaptocyclohexanone (II), cyclization of (II) with phosphorus pentoxide to 1:2:3:4-tetrahydrodibenzothiophene and selenium dehydrogenation of the latter compound to give (I) (overall yield 52%).
Starting with suitably substituted thiophenols, 2-methyl-, 3-methyl and 4-methyldibenzothiophenes and 4-methoxydibenzothiophene have been synthesized. The synthesis of 2-methoxydibenzothiophene could not be completed due to the low yield of 2-methoxy-6:7:8:9-tetrahydrodibenzothiophene. Attempts to cyclize 2-(4′-nitrophenylmercapto)cyclohexanone by means of phosphorus pentoxide by the usual method were unsuccessful.
The scope and limitations of the new synthesis are discussed.
Volume 37 Issue 1 January 1953 pp 114-119
With the view to study the significance of the 9∶10-phenanthrene double bond (“phenanthrene bridge”) in 9∶10-dimethyl-1∶2∶7∶8-dibenzanthracene (II), 6∶12-dimethylebenzo (1∶2
2∶7-Dimethoxyethylmercaptonaphthalene (IX) on cyclization gave thionaphtheno(4∶5∶4′:5′-)thionaphthene (VIII). The constitution (VIII) follows from the favoured α-cyclization in the naphthalene series and the similarity of its absorption spectrum with that of 3∶4-benzphenanthrene.
Volume 37 Issue 4 April 1953 pp 557-563
The dehydrogenation of 1∶2∶3∶4-tetrahydrodibenzothiophene (I) was studied by using various dehydrogenating agents in order to prepare dibenzothiophene (II) in optimum yield under mild conditions. Dehydrogenation by means of selenium or palladised carbon gave good yields of (II), but the reaction was carried out at high temperatures (>275°). By employing N-bromosuccinimide, the dehydrogenation could be carried out in a facile manner at lower temperatures (76°). These results are of value in the synthesis of derivatives of (II). Thus, whereas dehydrogenation of the chlorotetrahydrobenzothiafluorene (III) by treatment with selenium gave the benzothiafluorene (IV) by simultaneous dehydrogenation and dechlorination, dehydrogenation with N-bromosuccinimide gave the chlorine-containing benzothiafluorene (V).
Volume 37 Issue 4 April 1953 pp 564-570
The hitherto unknown angular benzo-9-thiafluorenes, 1∶2-benzo-9-thiafluorene (II) and 3∶4-benzo-9-thiafluorene (III) have been synthesized. The former was prepared starting from α-thionaphthol and 2-bromocyclohexanone. Condensation of these compounds gave 2-(α-naphthylmercapto) cyclohexanone (IV) which on cyclization and dehydrogenation gave (II). The constitution of (II) was proved by its unambiguous synthesis starting from 8-chloro-1-thionaphthol and 2-bromocyclohexanone. Starting from β-thionaphthol, (III) was prepared by similar steps. The constitution of (III) followed from its non-identity with 2∶3-benzo-9-thiafluorene.
Volume 38 Issue 4 October 1953 pp 271-276
Polycyclic thiophenes have been prepared starting from aryl thiols and 2-bromo-1-tetralone (1). Condensation of thiophenol with (I) gave 2-(phenylmercapto)-1-tetralone, which on cyclization gave 1:2-dihydro-3:4-benzo-9-thiafluorene. Dehydrogenation of the latter gave 3:4-benzo-9-thiafluorene (overall yield 72%). Starting from