ABSTRACT
It has been shown that the 1-NMe(2) group in the 2-substituted 1,8-bis(dimethylamino)naphthalenes (proton sponges) can intramolecularly donate a hydride ion to an appropriate electron-accepting ortho-substituent such as diarylcarbenium ion, ß,ß'-dicyanovinyl or methyleneiminium group. This produces the 1-N(+)(Me)=CH(2) functionality and triggers a number of further transformations (tert-amino effect) including peri-cyclization, ortho-cyclization or hydrolytic demethylation. In each particular case, the course of the reaction is determined by the nature of the ortho-substituent and the most potent nucleophile presenting in the reaction mixture. For 2,7-disubstituted 1,8-bis(dimethylamino)naphthalenes, two types of tandem tert-amino effect with the involvement of both peri-NMe(2) groups have been registered. The conclusion was made that proton sponges are generally more active in the tert-amino reactions than the corresponding monodimethylaminoarenes. This is ascribed both to higher electron donor ability of proton sponges and markedly shortened distance between electrophilic C(α)-atom in the ortho-substituent and hydrogen atoms of the nearest NMe(2) group. Most conversions observed proceed in good to high yields and are useful for the preparation of derivatives of benzo[h]quinoline, quino[7,8:7',8']quinoline, 2,3-dihydroperimidine, N,N,N'-trimethyl-1,8-diaminonaphthalene and proton sponge itself.
ABSTRACT
Crystals of the bis(ethylenedithio)tetraselenafulvalene (BETS) radical cation salt with dicyanamidomanganate(II) anion, kappa-(BETS)2Mn[N(CN)2]3, were synthesized, which combine conducting and magnetic properties at ambient pressure and are superconducting (Tc approximately/= 5 K) at a moderate pressure of 0.3 kbar.
ABSTRACT
Conformational study of 2-phenylazo-1-vinylpyrrole and 2-(4-bromophenyl)azo-5-methyl-1-vinylpyrrole was performed on the basis of the experimental measurements and high-level ab initio calculations of their 13C--13C and 13C--1H spin-spin coupling constants, showing marked stereochemical behaviour upon the internal rotation of the vinyl group and the pyrrolyl moiety. In liquid phase, both compounds were found to adopt predominant s-trans-s-trans conformation with the noticeable population (ca. 30%) of the higher-energy s-cis-s-trans conformation in the latter compound. As follows from the X-ray data, 2-phenylazo-1-vinylpyrrole crystallizes in s-trans-s-trans conformation while the crystalline molecular structure of 2-(4-bromophenyl)azo-5-methyl-1-vinylpyrrole is s-cis-s-trans.
