FORMATION OF NAPHTHOTHIOPHENES AND 1,2 DITHIOLE 3 THIONES FROM ISOPROPENYLNAPHTHALENES

1-Isopropenylnaphthalene was vulcanized with sulfur at 190°C to give 1-methylnaphtho-[2, l-6]thiophene [l a] and 4-(l-naphthyI)-l, 2-dithiole-3-thione [3 a]. 2-Bromo-l-methylnaphtho[2,l-6]thiophene [lb], obtained by the bromination of [1 a], afforded 1,2-dimethylnaphtho[2, l-b]thiophene [1 c] by the Grignard reaction. Similarly, 3-methylnaphtho[l, 2-b]-thiophene [2 a], 2-bromo-3-methylnaphtho[l, 2-b]thiophene [2 b], 2, 3-dimethylnaphtho[l, 2-b]-thiophene [2 c] and 4-(2-naphthyl)-l,2-dithiole-3-thione [3 b] were obtained from 2-isopro-penylnaphthalene. In order to confirm the site of the bromination in [1 b], 5-bromo-l-methylnaphtho[2, l-b]thiophene [6] was independently synthesized from 4-bromo-l-isopro-penylnaphthalene [5], and the spectral data of [6]were compared with those of [1 b]. The picrate of [5] showed a wide melting point range and [6] did not yield its picrate. The complexes of 2,4,7-trinitro-9-fiuorenone with [5] and [6] had the sharp meltine points of 124.5~125.5°C and 189~190°C, respectively. © 1978, The Chemical Society of Japan. All rights reserved.