Phthalimidesulfenyl Chloride; Part VII:¹Synthesis of 2-Substituted 3-Chlorobenzo[b]thiophenes and Related Heteroaromatics

Fused Thiophenes and Some Oligomers and Polymers Therefrom

“…Two equivalents of AlCl 3 were used to bring about cyclizing electrophilic substitution to make 40 from 39 (Scheme 9) [27].…”

Article

“…Specifically, 1propenesulfenic acid (3) has been shown to be the precursor of (Z)-and (E)-propanethial S-oxides (4), the familiar lachrymatory factor of onions (9). Unsaturated sulfenic acid amides have demonstrated usefulness in synthesis (10)(11)(12).…”

2,3‐Disubstituted Benzo[b]thiophenes from Diarylalkynes via Electrophilic Addition‐Cyclization and Palladium‐Catalyzed Cross‐Coupling

“…[10] Several years ago we reported an easy two-step (one-pot) procedure for the preparation of 3-chlorobenzo [b]thiophenes. [11] The method is based on the electrophilic addition of the phthalimidesulfenyl chloride PhtNSCl (Pht = Phthaloyl) to aryl-alkyl-or symmetrical diarylalkynes, to give (E)-b-chlorothiovinylphthalimides with high Markovnikov regioselectivity. These compounds under Lewis acid catalysis (AlCl 3 and BF 3 ·OEt 2 were demonstrated to be the reagents of choice) undergo an intramolecular electrophilic aromatic substitution with closure of the thiophene ring and elimination of the phthalimide residue (Scheme 1).…”

“…These compounds under Lewis acid catalysis (AlCl 3 and BF 3 ·OEt 2 were demonstrated to be the reagents of choice) undergo an intramolecular electrophilic aromatic substitution with closure of the thiophene ring and elimination of the phthalimide residue (Scheme 1). [11] In this paper, we describe an update of this methodology for the preparation of 2,3-disubstituted benzo [b]thiophenes of pharmaceutical interest exploiting the opportunities offered by some of the recent developments in organic synthesis. …”