http://pubs.acs.org/doi/pdf/10.1021/ol201062r

http://pubs.acs.org/doi/pdf/10.1021/jo201471k

http://www.ark.chem.ufl.edu/Published_Papers/PDF/1179.pdf

good luck

it depends on the nature of the substituents that you would like to have on the thiophene moiety 

Thanks everyone

Here please find a series of references for the straightforward synthesis of benzothiophene (extracted from ChemBrain IXL (http://neuronix.ch/chembrain)):

Comprehensive Heterocyclic Chemistry, Bird, C. W.; Cheeseman, G. W. H., Eds.; Pergamon: New York, (1984); Vol. 4.

Iddon, B.; Scrowston, R. M., Adv. Heterocycl. Chem., (1970) 11, 177.

Ple, P. A.; Marnett, L. J., J. Heterocycl. Chem., (1988) 25, 1271.

Gallagher, P.; Owton, W. M., Synth. Commun., (1989) 19, 2731.

Dann, O.; Kokorudz, M., Chem. Ber., (1958) 91, 172.

Rao, D. S.; Tilak, B. D., J. Sci. Ind. Res., Sect. B, (1959) 18, 77.

Titus, R. L.; Choi, M.; Hutt, M. P., J. Heterocycl. Chem., (1967) 4, 651.

Cabiddu, S.; Cancellu, D.; Floris, C.; Gelli, G.; Melis, S., Synthesis, (1988), 888.

Watanabe, M.; Date, M.; Kawanishi, K.; Akiyoshi, R.; Furukawa, S., J. Heterocycl. Chem., (1991) 28, 173.

Friedlander, P.; Lenk, E., Chem. Ber., (1912) 45, 2083.

Bridges, A. J.; Lee, A.; Maduakor, E. C.; Schwartz, C. E., Tetrahedron Lett., (1992) 33, 7499.

Angelini, C., Ann. Chim. (Rome), (1957) 47, 705.

Middleton, S., Aust. J. Chem., (1959) 12, 218.

Beck, J. R., J. Org. Chem., (1972) 37, 3224. Kolasa, T.; Brooks, D. W., Synth. Commun., (1993) 23, 743.

synthesis of benzothiophene the starting material is 2-chloroethyl  thiophenol which can be cyclized by heating under alkaline condition to get desired product.