The methylation of a series of 15 sodium 5-substituted tetrazolates using iodomethane in acetone/water (4 : 1) has been studied. The reaction yields both 1- and 2-methyl products, and the ratio of these products is discussed in terms of the nature of the 5-substituent. Electronic and steric effects dominate the reaction pathway; both increased substituent electro negativity and steric bulk lead to predominant methylation at N2. Sodium 5-ethoxycarbonyltetrazolate (3n) goes against this trend and an intermediate is proposed where the incoming electrophile is associated with the ester carbonyl group.

The reaction between 4,6-dinitrobenzofurazan 1-oxide (1) and a number of nucleophilic oxygen and nitrogen reagents has been studied. The exceptional electrophilic power of (1) leads to formation of 1 : 1 Meisenheimer complexes as the general reaction observed. Ammonia and hydrazine also form bis-adducts in the presence of excess (1). All the adducts were isolated as stable, but highly explosive, cystalline solids, and have been characterized by micro-analysis and spectroscopy. The adducts from N3- and I- have been observed spectroscopically but not isolated. The monomethoxy adduct (8) undergoes a novel internal oxidation-reduction to form a gem-dimethoxybenzofurazan complex(6).

Eighteen 1-methyl-1-phenylethyl (cumyl) (1) and 1-phenylethyl (styryl) (2) carbocations have been prepared in known concentration in FSO3H/SbF5 solution from their corresponding carbinols and their 1H and 13C spectra have been measured. The correlations of both the methyl 1H shifts [δH(Me)] and methyl 13C shifts [δC(Me)] with the cationic carbon shifts [δ(C+)] have been determined. In the case of δC(Me) curves are obtained indicating non-linearity of chemical shifts with charge density. Correlations of δ(C+) with Brown's σ+ constants are only fair, the deviation from linearity being interpreted in terms of non-linear dependence of either δ(C+) or σ+, or both, on charge density at this level of charge. The use of an enhanced substituent constant (σ++) and/or the dual substituent parameter equation improves the correlation. Non-linearity in the plot of δ(C 1) against σ+ reported for 2-arylnorborn-5-en-2-yl(4) and 2-arylnorbornan-2-yl cations (5) has been shown to occur also in the case of δC(Me) of the cumyl cations (1). The implications of this finding with respect to the structures of (4) and (5) are discussed.

Transoid homoallylic coupling constants (5JH,H) for six compounds (5,10-dihydroindeno[2,1-alindene and confertifolin derivatives) of fixed stereochemistry were determined and compared with calculated values. Magnetic equivalence limited discrete determination of 5Jtrans and 5Jcis to three of these compounds. The single compound where unequivocal assignment could be made revealed 5Jtrans > 5Jcis; this was supported in two other compounds by tentative assignment. Changes in the magnitude of the couplings suggested that substantial substituent effects may be operative. INDO-MO calculations correctly predicted the angular dependence but incorrectly predicted 5Jcis > 5Jtrans.

The uncatalysed formation of stable 1 : 1 Meisenheimer complexes between primary, secondary and tertiary aromatic amines and 4,6-dinitrobenzofurazan 1-oxide has been investigated. The thermodynamic product is derived from reaction through the aromatic carbon para or, if this position is substituted, ortho to the amino group of the aromatic amine. The complexes are stable to acid but react in aqueous potassium hydrogen carbonate solution or with aliphatic or aromatic amines to give crystalline salts of the complexes. In the presence of 1,4-diazabicyclo[2.2.2]octane, aniline reacts with 4,6-dinitrobenzofurazan 1-oxide to give an unstable nitrogen-bonded complex which is slowly converted into the carbon-bonded complex. The scope of the complexation reaction has been investigated and some of the mechanistic implications of the results are discussed.