Title: Condensed 1,3-benzothiazinones3. Synthesis of 3-substituted 1,2,4-triazolo[3,4-b][1,3]benzothiazin-5-ones
Abstract: Abstract Refluxing 2‐hydrazono‐3,4‐dihydro‐2 H ‐1,3‐benzothiazin‐4‐one 3 with triethyl orthoformate neat or with trimethyl orthoformate 4a , triethyl orthoacetate, orthopropionate, orthobenzoate 4b‐d in xylene gave 1,2,4‐triazolo[3,4‐ b ][1,3]benzothiazin‐5‐one 2a and its 3‐substituted derivatives 2b‐d in 56–95% yields. On the other hand, when 3 was treated with trifluoro‐, trichloroacetic anhydride 4e,f , dichloro‐, chloroacetyl chloride 4g,h , 2‐chloropropionyl and ethoxyoxalyl chloride 4i,j , the corresponding open‐chain condensates were produced, together with the title compounds 2g‐i , or the Dimroth rearrangement isomers 1e,g,i,j each depending on the reaction conditions. Nevertheless efficient preparation of 2h and 3‐hydroxy‐derivative 2k to get rid of such rearrangement was developed.
Publication Year: 1990
Publication Date: 1990-02-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 6
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