406935-63-5Relevant articles and documents
Substituted 1,3,2,4-benzodithiadiazines: Novel derivatives, by-products, and intermediates
Makarov, Alexander Yu,Bagryanskaya, Irina Yu,Gatilov, Yuri V.,Mikhalina, Tatiana V.,Shakirov, Makhmut M.,Shchegoleva, Lyudmila N.,Zibarev, Andrey V.
, p. 563 - 576 (2001)
The synthesis of the title compounds 1 by 1:1 condensation of Ar-N=S=N=SiMe32 with SCl2 followed by intramolecular ortho-cyclization of each [Ar-N=S=N-S-Cl] intermediate is complicated by further reaction of 1 with SCl2 to give Herz salts 3. With the 2:SCl2 ratio of 2:1, the formation of by-products 3 is reduced and novel compounds 1 are accessible. With ortho-I containing starting material 2j, the parent compound 1s is obtained as the result of an unexpected I, not H, substitution. The rate of the 1 + SCl2 reaction depends upon a substituent's position, and the minor 8-R isomers 1l,p (R=Br, I) are isolated for the first time from mixtures with the major 6-R isomers due to reduced reactivity toward SCl2. The synthesized compounds 1-3 are characterized by multinuclear (including nitrogen) NMR and X-ray crystallography. According to the X-ray diffraction data, 1j (6-Br) and 1k (7-Br) derivatives are planar, whereas 1i (5-Br) and 11 (8-Br) are bent along the S1···N4 line by ～5° and ～4°, respectively, and the 1r (7-OCH3) derivative is planar in contrast to the known 5-OCH3 isomer, which possesses a significantly folded heterocycle. The distortion of the planar geometry of some compounds 1 is interpreted in terms of a pseudo-Jahn-Teller effect as the result of π-highest occupied molecular orbital (HOMO) - σ*-(LUMO) lowest unoccupied molecular orbital + 1 mixing in a planar conformation. The 2p compound is the first structurally defined Ar-N=S=N-SiMe3 azathiene. The compound Ar-N=S=N-S-NH-Ar 6 modeling the aforementioned intermediate has been isolated and structurally characterized. We describe the attempts to synthesize compounds 1 from 2-aminobenzenethiols and (SN)4 and from salts 3 and Me3SiN3, and we discuss the reaction pathways.
