Attachment of a Heterocycle to Naphthalene or Anthracene Nuclei

On photolysis or thermolysis of the peri-methylmercapto-substituted sodium salt of a-naphthaldehyde tosyl hydrazone 77 or diazomethyl-naphthalene 78, 2//-2-methylnaphtho[frc]thiophene 80 (83JA6096) is formed in 20% yield. Ylid 79 may be a predecessor of thiophene 80. In 

If a blocking substituent is situated ortho to the propionyl fragment, electrophilic attack is directed only to the neighboring peri-position. In the absence of such a substituent, a mixture of ortho- and peri-annelated isomers 96 and 97 has been obtained. On heating with chloranil, dihydro ketones 94 and 97 undergo dehydrogenation to 5- and 3-naphtho[bc]thio-phenones 95 and 98. 

The formation of naphtho[6c]thiophene-3-ones 106 takes place on acylation of 2-substituted benzo[b]thiophenes 103 with cinnamoyl chloride (78AP710, 78LA627 79LA965). Interestingly, the aromatization of the intermediate 105 occurs with elimination of benzene. Chalcone 104 also may be obtained on acetylation of benzo[fe]thiophene 103, followed by condensation of benzaldehyde with the methyl group of the 3-acetylbenzo[b]thiophene intermediate (79LA965). 

Naphtho[ c]thiophenones 108 can be synthesized in one step on acylation of 2-substituted benzo[6]thiophenes 107 with malonic acid 

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