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Umsetzungen von 1,3‐Thiazol‐5(4 H )‐thionen mit Grignard ‐ und Organolithium‐Verbindungen: Carbophile und Thiophile Additionen
Author(s) -
Jenny Christjohannes,
Heimgartner Heinz
Publication year - 1986
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.19860690404
Subject(s) - chemistry , alkylation , protonation , medicinal chemistry , organolithium compounds , isopropyl , benzonitrile , thiazole , reagent , grignard reagent , bromide , yield (engineering) , allyl bromide , deprotonation , stereochemistry , ion , organic chemistry , catalysis , materials science , metallurgy
Reactions of 1,3‐Thiazole‐5(4 H )‐thiones with Grignard ‐ and Organolithium Compounds: Carbophilic and Thiophilic Additions Organolithium compounds and 1,3‐thiazole‐5(4 H )‐thiones 9 reacted via thiophilic addition on the exocyclic S‐atom. The intermediate anion E has been trapped by protonation to give 12 and by alkylation to yield 16 , respectively ( Schemes 5 and 6 ). In competition with protonation of E , a fragmentation to benzonitrile and a dithioester 14 was observed (Scheme 5) . In some cases, the alkylation of E led to the formation of dithioacetals 17 instead of 16 (Scheme 6) . Methyl, ethyl, and isopropyl Grignard reagents and 9 in THF underwent again a thiophilic addition yielding 4,5‐dihydro‐1,3‐thiazoles of type 12 (Scheme 3) . In contrast to this result, MeMgI reacted with 9a in Et 2 O via carbophilic addition to 11 . Again a carbophilic attack at C(5) of 9 was observed with allylmagnesium and 2‐propynylmagnesium bromide, respectively, in Et 2 O.