Switchable Synthesis of 4,5-Functionalized 1,2,3-Thiadiazoles and 1,2,3-Triazoles from 2-Cyanothioacetamides under Diazo Group Transfer Conditions.
High yield solvent-base-controlled, transition metal-free synthesis of 4,5-functionalized 1,2,3-thiadiazoles and 1,2,3-triazoles from 2-cyanothioacetamides and sulfonyl azides is described. Under diazo transfer conditions in the presence of a base in an aprotic solvent 2-cyanothioacetamides operating as C-C-S building blocks produce 5-amino-4-cyano-1,2,3-thiadiazoles exclusively. The use of alkoxide/alcohol system completely switches the reaction course due to the change of one of the reaction centers in the 2-cyanothioacetamide (C-C-N building block) resulting in the formation of 5-sulfonamido-1,2,3-triazole-4-carbothioamide sodium salts as the only products. The latter serve as good precursors for 5-amino-1,2,3-thiadiazole-4-carboximidamides, the products of Cornforth-type rearrangement occurring in neutral protic medium or under acid conditions. According to DFT calculations (B3LYP/6-311+G(d,p)) the rearrangement proceeds via intermediate formation of a diazo compound, and can be catalyzed by acids via the protonation of oxygen atom of the sulfonamide group.
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Valeriy O
0000-0001-6067-7150
VO
Filimonov
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Lidia N
LN
Dianova
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Kristina A
KA
Galata
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Tetyana V
TV
Beryozkina
Institute of Chemistry, St. Petersburg State University , 7/9 Universitetskaya nab., St. Petersburg 199034, Russia.
Mikhail S
0000-0001-5106-4723
MS
Novikov
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Vera S
VS
Berseneva
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Oleg S
OS
Eltsov
Department of Chemistry, Lomonosov Moscow State University , Moscow 119991, Russia.
Albert T
AT
Lebedev
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.|I. Ya. Postovsky Institute of Organic Synthesis, Ural Branch of Russian Academy of Sciences , 20 S. Kovalevskaya st., Yekaterinburg 620990, Russia.
Pavel A
PA
Slepukhin
Ural Federal University named after the first President of Russia B. N. Yeltsin , 19 Mira st., Yekaterinburg 620002, Russia.
Vasiliy A
0000-0002-3312-7783
VA
Bakulev