Photolytic transformations of p-quinones

Quantum yields, apparent photolysis rate constants, and energies of activation of the dark stages in the decomposition of 3,6-di-tert-butyl-2,3-epoxy-5-hydroxycyclohex-2-ene-1,4-dione, 1,4-naphthoquinone, and 9,10-anthraquinone under irradiation at λ 313 nm and of 1,4-benzoquinone under irradiation at λ 232–254 nm were determined. Products of photochemical transformations of these compounds in saturated hydrocarbons were identified, and a probable mechanism of these transformations was proposed.     

Reaction of bis(hydroxymethyl)phenylphosphine oxide with isobutyl diphenylborate in the presence of amines

Conclusions The reaction of bis(hydroxymethyl)phenylphosphine oxide with isobutyl diphenylborate catalyzed by secondary and tertiary amines as well as by ammonia leads to ammonium 2,2,5-triphenyl-5-oxo-1, 3,2,5-dioxaborataphosphorinanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 187–189, January, 1988.     

Dipolar cycloaddition of rhodium-generated carbonyl ylides with p-quinones

[reaction: see text] The dipolar cycloaddition of carbonyl ylides generated by the rhodium-catalyzed decomposition of delta- and epsilon-carbonyl-alpha-diazoketones with p-quinones leads to both C=O and C=C addition products. The product ratio is solvent- and catalyst-dependent and has been optimized to favor formation of either product. The C=C addition products of naphthoquinones are used in the assembly of structures hybridizing the illudin and anthraquinone anticancer agents.     

Reactions of perfluoronitriles. II. Interactions with phenylphosphine

Treatment of perfluoro-n-octanonitrile with phenylphosphine gave tetraphenyltetraphosphine and a spectrum of reduction and interaction products. Fifteen compounds were identified. The imine, (R_fC₇F₁₅) R_fCHNH, and the amine, R_fCH₂NH₂, were the primary reduction products. Secondary phosphorus-free products, some formed following ammonia evolution, were the following: R_fCHNCH₂R_f, R_fCH₂CH(NH₂)R_f, R_fC(NH)NCR_f(NH₂), R_fCH₂NHCR_f(NH), (R_fCN)₃, R_fCHNCR_fNCR_f(NH), R_fCH₂NCR_fNHCH₂R_f, and R_fCH₂NCR_fNHCR_f(NH). Only three phosphorus-containing materials were definitely identified: R_fCH(NH₂)P(C₆H₅)H, R_fCH[P(C₆H₅)H]NCHR_f, and R_fC(NH)P(C₆H₅)CR_f(NH). Depending on reaction conditions, specific phosphorus-containing compounds could be preferentially produced. All the structure assignments are based solely on mass spectral breakdown patterns, since pure compounds were not isolated.     

Direct access to 1,4-dihydroxyanthraquinones: the Hauser annulation reexamined with p-quinones

3-Phenylsulfanylphthalides (e.g. 8a) readily react with p-benzoquinones in the presence of LiOtBu in THF to furnish 1,4-dihydroxyanthraquinones in good yields and one-pot operations.     

Organophosphorus compounds—XIX : The reaction of trialkyl phosphites with extended p-quinones

Trimethyl and triethyl phosphites react with diphenoquinone 3, yielding 4,4′-dihydroxydiphenyl 10; 4′-alkoxy-4-biphenylyl dialkyl phosphates 5, 4,4′-biphenylylene tetraalkyl bis(phosphates), 6, and 4′-hydroxy-4-biphenylyl dialkyl phosphates 9 are also isolated in minor yields. The effect of temperature on the reaction is studied. A mechanism for the reaction is presented which accounts for the experimental results. The reaction of trimethyl and triethyl phosphites with quinoneimines 12 gives the corresponding phosphoramidates 13, in quantitative yields.     

A novel degradative strategy for the synthesis of p-quinones.

p-Hydroxybenzylalcohols undergo Fremy's salt promoted degradative oxidation to give the corresponding p-benzoquinones. A novel strategy for the synthesis of p-benzoquinones based on the regioselective metalation of 2-methoxy-4-methoxymethyl phenols is presented.     

Electron affinity of p-quinones. Improved method of electrochemical estimation

Electron affinities of four p-quinones are estimated from enthalpy changes obtained on the basis of measured formal potentials and reaction entropies in the electroreduction process. A linear correlation between electron affinities of p-quinones and parent hydrocarbons is found.     

Polymerization of alkyl (meth)acrylates in the presence of p-quinones

Russian Chemical Bulletin - The azobisisobutyronitrile-initiated polymerization of methyl methacrylate, butyl methacrylate, and butyl acrylate at 60 °C in the presence of p-quinones differing...     

The photoelectron spectrum and conformation of phenylphosphine and phenylarsine

He(I) and He(II) photoelectron spectra of phenylphosphine and phenylarsine have been investigated and assigned. The rotational barrier of the phosphino group has been investigated at the MP2/6-31G(d,p)//MP2/6-31G(d,p) and HF/6-31G(d,p)//HF/6-31G(d,p) levels of theory, and that of the arsino group at the HF/6-31G(d,p)//6-31G(d,p) levels of theory. The rotational barrier of the two molecules is nearly the same. The energy difference between the two possible conformers of the molecules is low (1.5 kJ/mol at the MP2/6-31G(d,p) level of theory), allowing nearly free rotation about the P-C bond. The photoelectron spectrum cannot be interpreted by considering the most stable rotamer, but all possible conformers should be taken into account. The present interpretation is consistent with the smalln _p - interaction concluded from other investigations. The rotational barrier ofo-phosphinophenol is significantly larger than for phenylphosphine, and the photoelectron spectrum of this compound can be interpreted by considering a single conformer, and no appreciable interaction between the -system of the ring and the phosphorus lone pair.     

Ring-chain tautomerism of complexes of diphenylboryloxymethyl-(hydroxymethyl)phenylphosphine sulfide with amines

Conclusions Complexes of diphenylboryloxymethyl(hydroxymethyl)phenylphosphine sulfide exist in both open and cyclic forms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2089–2093, September, 1984.     

Enzyme-promoted desymmetrisation of prochiral bis(cyanomethyl)phenylphosphine oxide

Prochiral bis(cyanomethyl)phenylphosphine oxide has been successfully transformed into the corresponding optically active monoamide and monoacid with enantiomeric excesses ranging from low (15%) to very high (up to 99%) using a broad spectrum of nitrile-hydrolysing enzymes.     

Green protocol for conjugate addition of amines to p-quinones accelerated by water

Amines undergo smooth conjugate addition to p-quinones in H₂O at ambient temperature in the absence of a catalyst to produce 2-aminoquinones in excellent yields. Significant rate acceleration of this reaction is observed in H₂O compared to organic solvents. H₂O played a dual role in simultaneously activating the p-quinone and amine. This new methodology constitutes an easy, highly efficient, and green synthesis of substituted p-quinones. Correspondence: J. S. Yadav, Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500007, India.