Correlation of the product E/Z framework geometry and O/O vs O/N regioselectivity in the dialkylation of hyponitrite

The products from the alkylation of silver hyponitrite with tert-butyl brom ide, tert-amyl bromide, p-tert-butyl benzylbromide, and chlorotriethylsilan e have been determined. In the reaction of tert-butyl bromide the formation of three new products, namely, (Z)-N-tert-butyl-N'-tert-butoxydiazene-N-ox ide {(CH3)(3)CN(O)NOC(CH3)(3)}, 1D, trans-mono-O-tert-butylhyponitrous acid {(CH3)(3)CONNOH}, 2A, and (Z)-N-tert-butyl-N'-hydroxydiazene-N-oxide {(CH3 )(3)CN(O)NNQH}, 2D, is observed together with the formation of the known tr ans-di-O-tert-butyl hyponitrite {(CH3)(3)CONNOC(CH3)(3)}, 1A. The reaction with tert-amyl bromide also yielded the corresponding tert-amyl derivatives . However, from the reactions of p-tert-butylbenzyl bromide and chlorotriet hylsilane with silver hyponitrite, the corresponding trans-di-O-tert-alkylh yponitrites were obtained as the only alkylated products. The differential reactivity of the two sets of halides with silver hyponitrite is explained in terms of the higher stability of the cations generated from the former h alides in comparison to those generated from the latter halides. The therma l decomposition data and UV-visible spectroscopic data are reported for all of the products. Crystallographic structural data are reported for two of the products, namely, Q-N-tert-butyl-K-tert-butoxydiazene-N-ox, 1D, as its hyponitrous acid adduct, (CH3)(3)CN(O)NOC(CH3)(3). 1/2HONNOH, and trans-di- O-p-tert-butylbenzyl hyponitrite, {p(CH3)(3)C}C6H4CH2ONNOCH2C6H4-p-{C(CH3)( 3)}. Theoretical calculations using ab initio density functional theory (B3 LYP) are reported for the hyponitrite dianion, trans-mono-O-methylhyponitri te anion, (Z)-N-methyl-N'-hydroxylatodiazene-N-oxid anion, and for the meth ylation transition states. On the basis of the products isolated from the r eactions of tert-butyl bromide and tert-amyl bromide and the theoretical ca lculations, a pathway is proposed to account for the observed product distr ibutions where O/O-dialkylation is found in the trans(E) products and O/N-d ialkylation is found in the cis(Z) products.