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One‐Pot Syntheses of 2‐(2‐Sulfanyl‐4 H ‐3,1‐benzothiazin‐4‐yl)acetic Acid Derivatives via Reactions of 3‐(2‐Isothiocyanatophenyl)prop‐2‐enoic Acid Derivatives with Thiols or Sodium Sulfide
Author(s) -
Fukamachi Shuhei,
Konishi Hisatoshi,
Kobayashi Kazuhiro
Publication year - 2011
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201000340
Subject(s) - sulfanyl , chemistry , acetic acid , moiety , dithiocarbamate , medicinal chemistry , alkyl , aryl , organic chemistry , stereochemistry
Two efficient methods for the preparation of 2‐(2‐sulfanyl‐4 H ‐3,1‐benzothiazin‐4‐yl)acetic acid derivatives 3 under mild conditions have been developed. The first method is based on the reaction of 3‐(2‐isothiocyanatophenyl)prop‐2‐enoates 1a – 1c with thiols in the presence of Et 3 N in THF at room temperature, leading to the corresponding dithiocarbamate intermediates 2 , which underwent spontaneous cyclization at the same temperature by an attack of the S‐atom at the prop‐2‐enoyl moiety in a 1,4‐addition manner ( Michael addition) to give 2‐(2‐sulfanyl‐4 H ‐3,1‐benzothiazin‐4‐yl)acetates in one pot. The second method involves treatment of 3‐(2‐isothiocyanatophenyl)prop‐2‐enoic acid derivatives 1b – 1d with Na 2 S leading to the formation of 2‐(2‐sodiosulfanyl‐4 H ‐3,1‐benzothiazin‐4‐yl)acetic acid intermediates 5 by a similar addition/cyclization sequence, which are then allowed to react with alkyl or aryl halides to afford derivatives 3 . 2‐(2‐Thioxo‐4 H ‐3,1‐benzothiazin‐4‐yl)acetic acid derivatives 6 can be obtained by omitting the addition of halides.