N-S rearrangements

The N - S rearrangements of furazan and furoxan derivatives will be discussed in the appropriate section. 

An S-)-N rearrangement has been reported in the cysteine derivative (29), shown in Scheme 6.17. In methanol, the addition of a base such as Dabco is required, while in DMF or DMSO, the reaction is much faster and does not require added base [105]. Interestingly, in the presence of added base in DMF, the anionic intermediate (30) is observable spectroscopically, and due to ionization of the thiol group in (31), the reverse N S rearrangement occurs to give a mixture of (29) and (31). 

Formation of five-member N,S- and N-heterocycles by sigmatropic rearrangements of functionalized allenes 97FA2005. 

The nickel(II) dithiocarbamate complexes are neutral, water-insoluble, usually square-planar, species, and they have been studied extensively by a range of physical techniques. The usual methods for the synthesis of dithiocarbamate complexes have been employed in the case of Ni(II), Pd(II), and Pt(II). In addition, McCormick and co-workers (330,332) found that CS2 inserted into the Ni-N bonds of [Ni(aziri-dine)4P+, [Nilaziridinelgf, and [Ni(2-methylaziridine)4] to afford dithiocarbamate complexes. The diamagnetic products are probably planar, but they have properties typical of dithiocarbamate complexes, and IR- and electronic-spectral measurements suggested that they may be examples of N,S-, rather than S,S-, bonded dithiocarbamates. The S,S-bonded complexes are however, obtained, by a slow rearrangement in methanol. The optically active lV-alkyl-iV(a-phenethyl)dithio-carbamates of Ni(II), Pd(II), and Cu(II) (XXIV) have been synthesized, and the optical activity was found to be related to the anisotropy of the charge-transfer transitions (332). 

Characteristic for the fragmentation of the title compounds (237-243) are a very facile N—S bond cleavage (route A in equation 50 giving rise to 244) as in sulfonylhydrazides (Section V.C) and skeletal rearrangements accompanied by the extrusion of SO2 from the M and [M — 1] ions to the ionized JV-aryliminopyridinium betaines (245, compounds 237-239) or AT-imino-2-benzylpyridinium betaines (247, compounds 240-243 in equation 52) and azacarbazoles (246), respectively . Ion 244 decomposes further by elimination of HCN and via the loss of R N and HCN, as shown in equation (51). The sequence M " (240-243)- 247 ->248 (equation 52) is supported by the fact that AT-imino-a-alkylpyridinium betaines can lose an NH2 radical due to the operation of an ortho effect . 

Nadzhafova, R.S., N.S. Bulatova, A.I. Kozlovskii, and I.N. Ryabov. 1994. Identification of a structural chromosomal rearrangement in the karyotype of a root vole from Chernobyl. Russian Jour Genet. 30 318-322... 

On reacting with unsaturated reagents, 5-iminothiadiazolines 252 give rearrangements involving N—S bond fission (Scheme 42). Thus, the imino... 

N Claisen rearrangement.3 This Pd(II) salt permits the rearrangement of S- llylthioimidates to N-allylthioamides. Tetrakis(triphcnylphosphine)palladium and various other metal salts are inactive. The rearrangement is inhibited by a substituent til the 2-position of the allyl group. 

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