Polarization phenomena under fast electron scattering by deuterons

The polarization of nucleons, which arises in deuteron electrodisintegration as a function of the angle between nucleon trajectories is considered. In electron scattering by large angles the polarization is affected by the interaction in the final state as well as by the presence of a D-wave component in the deuteron ground state. It is shown that the polarization degree of producing nucleons essentially depends on the choice of radial parts of the deuteron wave-function and the D-wave contribution in the deuteron ground state.     

Syntheis of amino-substituted 1,3-bis(tert-butyl-NNO-azoxy)benzenes

Oxidation of 4,6-dichloro-1,3-phenylenediamine with Caro's acid yields the corresponding dinitrosobenzene, which reacts withN,N-dibromo-tert-butylamine to give 1,5-bis(tert-butyl-NNO-azoxy)-2,4-dichlorobenzene. Treatment of the latter with ammonia yields 4-amino-and 4,6-diamino-1,3-bis(tert-butyl-NNO-azoxy)benzenes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 7, pp. 1307–1310, July, 1999.     

The chemistry ofN,N-bis (trialkylsilyloxy) enamines

The reactions of primary amines withN,N-bis(trimethylsilyloxy) enamines can give products of both mono-and bis-α-oximinoalkylation of primary amines. The steric restrictions in both reactants substantially retard bis-α-oximinoalkylation. A general method for the synthesis of α-amino-substituted oximes from primary amines and bis-silyl derivatives of aliphatic nitro compounds was developed. For Part 1, see Ref. 1. Published inIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1265–1272, July, 2000.     

Synthesis of 5-amino-6-nitro-1,2,3,4-tetrazine 1,3-dioxide

5-Amino-(tert-butyl-NNO-azoxy)-1,2,3,4-tetrazine 1,3-dioxide reacts with nitronium tetra-fluoroborate to give 5-amino-6-nitro-1,2,3,4-tetrazine 1,3-dioxide. This compound is of interest as a new energetic material. A plausible reaction mechanism involves electrophilic substitution of the tert-butyl-NNO-azoxy group by the nitro group.

     

Synthesis of PDE IVb inhibitors. 1. Asymmetric synthesis and stereochemical assignment of (+)- and (-)-7-[3-(cyclopentyloxy)-4-methoxyphenyl]hexahydro-3H-pyrrolizin-3-one

Asymmetric synthesis of GlaxoSmithKline's highly potent phosphodiesterase inhibitor 1 has been accomplished in nine steps and 16% overall yield. The original strategy suggested involves as a key step the silylation of enantiopure six-membered cyclic nitronates 4 obtained by a highly stereoselective [4 + 2]-cycloaddition of an appropriate nitroalkene 5 to trans-1-phenyl-2-(vinyloxy)cyclohexane. Functionalization of the resulting 5,6-dihydro-4H-1,2-oxazine and subsequent stereoselective reduction of 1,2-oxazine ring in intermediate 2 furnished the pyrrolizidinone framework with the recovery of chiral auxiliary alcohol.     

Reaction of N-nitro-O-(4-nitrophenyl)hydroxylamine with phosphorus pentoxide in the presence of nitriles. New method for the generation of aryloxenium ion

A reaction of N-nitro-O-(4-nitrophenyl)hydroxylamine with nitriles RCN (R = Me, Et, Ph) in the presence of P₄O₁₀ in excess amount at 0 °C leads to the formation of 2-R-5-nitro-1,3-benzoxazoles. The reaction presumably takes place through the intermediate (phenoxy)oxodiazonium ion [NO₂C₆H₄O-N=N=O]⁺, which eliminates an N₂O molecule to form the aryloxenium ion [NO₂C₆H₄O]⁺. The latter reacts with nitriles RCN at the ortho-carbon atom of the phenyl ring giving 2-R-5-nitro-1,3-benzoxazoles.     

Generation of oxodiazonium ions 4. Nitramine O-alkyl derivatives in the synthesis of benzotetrazine-1,3-dioxides

A new method for the synthesis of benzotetrazine-1,3-dioxides was developed from the 2-(tert-butyl-NNO-azoxy)-N-nitroaniline O-alkyl derivatives upon the action of strong acids (H₂SO₄, MeSO₃H, CF₃CO₂H) or BF₃·Et₂O. A mechanism suggested for these reactions includes transformation of the N=N(O)OR group (R = Me, Prⁱ) to the oxodiazonium ion (N=N=O)⁺, which intramolecularly reacts with the neighboring tert-butyl-NNO-azoxy group, furnishing the tetrazine-1,3-dioxide ring.