Premium
Condensed 1,3‐benzothiazinones 3 . Synthesis of 3‐substituted 1,2,4‐triazolo[3,4‐ b ][1,3]benzothiazin‐5‐ones
Author(s) -
Liu KangChien,
Shih BiJane,
Chern JiWang
Publication year - 1990
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570270253
Subject(s) - triethyl orthoformate , chemistry , chloroacetyl chloride , derivative (finance) , chloride , medicinal chemistry , organic chemistry , catalysis , financial economics , economics
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.