Oxygenation of 4-(N-alkylimino)methyl-2,6-di-t-butylphenols mediated by Co(II)-Schiff base complex

4-(N-Alkylimino)methyl-2,6-di-$\text{t}$-butylphenols ($\text{1}$), Schiff bases of 3,5-di-$\text{t}$-butyl-4-hydroxybenzaldehyde can be oxygenated in the presence of Co(Salpr), a five coordinate Co(II)-Schiff base complex to give N-alkyl-3-$\text{t}$-butyl-5-formyl-2-hydroxy-2-pivaloyl-1,2-dihydropyridines ($\text{2}$ as the main product together with 3-formyl-2,5-di-$\text{t}$-butyl-2,4-cyclopentadienone ($\text{3}$) and 2,6-di-$\text{t}$-butyl-4-formyl-6-hydroxy-4,5-epoxy-2-cyclohexenone ($\text{4}$). These products result from dioxygen incorporation into the ortho position of $\text{1}$.     

Oxygenation of 2,6-di-t-butylphenols bearing electron-withdrawing group at 4-position mediated by Co(II)-schiff base complex

4-Acyl-2,6-di-$\text{t}$-butylphenols except 3,5-di-$\text{t}$-butyl-4-hydroxybenzaldehyde were oxygenated in the presence of Co(Salpr) exclusively at the ortho position to give the corresponding 3,5-di-$\text{t}$-butyl-6-hydroperoxy-2,4-cyclohexadienone derivatives in quantitative yield.     

A new route to 3-alkyl-2,5-di-t-butyl-2,4-cyclopentadienones from 4-alkyl-2,6-di-t-butylphenols

Base-catalyzed reaction of 5-acylmethyl-2,5-di-$\text{t}$-butyl-4-oxa-2-cyclopentenones selectively derived from 4-alkyl-2,6-di-$\text{t}$-butylphenols $\text{via}$ three steps involving oxygenation, acetylation, and acid-treatment gave 3-alkyl-2,5-di-$\text{t}$-butyl-2,4-cyclopentadienones in excellent yield.     

Conformation,in solution,of c-4-t-butyl-1-phenyl-r-1-(N-piperidyl)cyclohexane hydrochloride. The conformational energy of t-butyl

Although the hydrochloride of $\text{c}$-4-$\text{t}$-butyl-1-phenyl-$\text{c}$-1-(N-piperidyl)cyclohexane crystallizes in the conformation with axial $\text{t}$-butyl, it exists as an almost equimolar mixture of the two chair conformers in CD₂ Cl₂ solution. The position of equilibrium allows one to calculate ΔG°_{$\text{t}$-Bu} as ?4.9 kcal/mol.     

Potential metabolites of carcinogenic aza aromatic hydrocarbons synthesis of K-region oxide,phenol and dihydrodiols of 7-methylbenz[c]acridine

The potential K-region metabolites, $\text{trans}$- and $\text{cis}$-5,6-dihydroxy-7-methyl-5,6-dihydrobenz[c]acridine, 5,6-epoxy-7-methyl-5,6-dihydrobenz[c]acridine and 5-hydroxy-7-methylbenz[c]acridine, of 7-methylbenz[c]acridine have been synthesised.     

A new carotenoid,halocynthiaxanthin from the sea squirt, halocynthiaroretzi

A new carotenoid, halocynthiaxanthin (5,6-epoxy-3,3′-dihydroxy-7′,8′-didehydro-5,6,7,8-tetrahydro-β,β-caroten-8-one) has been isolated from the Japanese sea squirt, $\text{Halocynthia}$ roretzi.     

Synthesis of (+)-galantinic acid,a constituent amino acid in the peptide antibiotic galantin I, via the stereoselective epoxidation of a chiral serine equivalent

Epoxidation of (2$\text{R}$)-$\text{t}$-butoxycarbonylamino-3-butenol afforded, in a highly stereo-selective manner, a $\text{threo}$-3,4-epoxy-2-aminobutanol derivative which was successfully converted to the unusual amino acid (+)-galantinic acid in 8 steps $\text{via}$ regiospecific epoxide ring opening with divinyl cuprate.     

Reaction of superoxo Co(III) complexes with 2,6-di-t-butyl-p-benzoquinone methides

Superoxo Co(III) complexes derived from Co(Salpr) and [Co(CN)₅]^3? reacted with 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone methides to give 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone and 2,6-di-$\text{t}$-butyl-2,5-cyclohexadienonespirooxiranes as the main products, which are considered to result from nucleophilic attack by the superoxo species on the exo double bond of the quinone methides.     

Mechanism of selective p-quinol formation in the cobalt schiff base complex-catalyzed oxygenation of 4-alkyl-2,6-di-t-butylphenols

The selective formation of $\text{p}$-quinols in the Co(Salpr)-catalyzed oxygenation of 4-alkyl-2,6-di-$\text{t}$-butylphenols in MeOH has been found to involve the rate determining reduction of peroxy-$\text{p}$-quinolato Co(III) complex formed in the initial fast step. An ionic mechanism of the reduction of the OO bond in the peroxy complex by MeOH has been discussed based on kinetic studies. The reactive species in the catalytic cycle is found to be [Co(III)(Salpr)(OH)].     

A general synthesis of primary prostaglandins

Combination of ($\text{R}$)-4-$\text{t}$-butyldimethylsiloxy-2-cyclopentenone, ($\text{S}$)-($\text{E}$)-3-$\text{t}$-butyldimethylsiloxy-1-iodo-1-octene, and 6-methoxycarbonyl-2-hexynal via the tandem organo-copper conjugate addition—aldol reaction procedure leads directly to a 5,6-dehydroprostaglandin E₂ derivative, which can be transformed to a variety of chiral primary prostaglandins in a stereoselective manner.     

Towards tetrasilabicyclo[1.1.0]butane: reductive coupling of 1-t-butyl-2,2-dimesityl-1,1,2-trichlorodisilane

Reductive coupling of 1-$\text{t}$-butyl-2,2-dimesityl-1,1,2-trichlorodisilane employing Li-naphthalenide furnishes, on oxygenation or hydrolysis of the reaction mixture, products ($\text{8}$-$\text{11}$) that may arise from insertion of oxygen into or the addition of water across the Si-Si bonds of 1,3-di-$\text{t}$-butyl-2,2,4,4-tetramesityltetrasilabicyclo-[1.1.0]butane ($\text{3}$).     

Bifunctional initiators—I. Synthesis and characterization of 4,4′-azobis(4-cyanovaleryl)bisbenzoyl and bisacetyl diperoxides

The paper refers to the synthesis and properties of some bifunctional initiators, viz. 4.4′-azo-bis(4-cyanovaleryl)bisbenzoyl diperoxide (I) and 4,4′-azobis(4-cyanovaleryl)bisacetyl diperoxide (II), obtained from the acid chloride of cyanovaleric acid and condensed with perbenzoic acid or peracetic acid. The structures of the products were established by i.r. and NMR spectroscopy, as well as by elemental analysis. Kinetic studies on the thermolyses of the two initiators led to the following results: for I. $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{azo, 360°K = 129 min}$, $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{peroxy, 360°K = 245 min}\text{, E}{}_{\mathrm{<mtext>azo</mtext>}}\text{=}\text{174.2 kJ/mol}\text{, E}{}_{\mathrm{<mtext>peroxy</mtext>}}\text{=}\text{206.5 kJ/mol}$; for II, $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{azo, 357°K = 152 min}\text{, t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{peroxy, 357°K = 208 min}\text{, E}{}_{\mathrm{<mtext>azo</mtext>}}\text{=}\text{155.4 kJ/mol}\text{, E}{}_{\mathrm{<mtext>peroxy</mtext>}}\text{=}\text{188.5 kJ/mol}$.     

Photochemically induced reaction of 1, N4-dimethylcytosinewith isopropanol

Photoexcited 1, $\text{N}$⁴-dimethylcytosine (I) adds isopropanol to form 5,6-dihydro-1, $\text{N}$⁴-dimethyl-6-(2-hydroxy-2-propyl)cytosine (II) as the major product; a small amount of 5,6-dihydro-1-methyluracil (III) is formed as well.     

Addition conjuguee d'equivalents d'acyles aux cyclohexen-2 ones et a la Δ1(9) octalone-2: Synthese de dicetones 1–4.

The synthesis of 3-acetylcyclohexanones $\text{11}$, $\text{12}$, $\text{13}$ has been realized by conjugate addition of lithiated cyanohydrin ether $\text{1a}$ to 2-cyclohexenones $\text{2}$, $\text{3}$, $\text{4}$ in THF-HMPA, even if 3-substituted. 3-benzoylcyclohexanones $\text{14}$, $\text{15}$, $\text{16}$ are obtained from $\text{1b}$ and $\text{2}$, $\text{3}$, $\text{4}$ in THF with excellent yields.     

Applications of the thermal ene reaction of aldehyde t-butyl- and phenyl- hydrazones

The Thermal Ene reaction of aldehyde $\text{t}$-butyl- and phenyl- hydrazones with enophiles gave $\text{C}$-trapped azo-adducts which can be diverted into synthetically useful γ-keto-esters, γ-keto-nitriles, γ-alkyl-2-pyrrolidones, and γ-amino-esters.     

A stereoselective 3-endo-alkyl-5,6-dehydroisoquinuclidine synthesis.

Cycloaddition of N-carbethoxy-2-alkyl-1,2-dihydropyridines $\text{4}$ with phenylvinylsulfone $\text{5}$ provides adducts $\text{6}$, which upon desulfonylation afford stereoselectively N-carbethoxy-3-$\text{endo}$- alkyl-5,6-dehydroisoquinuclidines $\text{1}$.     

All-trans-1-acyloxy-1,3-pentadiene-5 ols as reactive dienes in new intramolecular diels-alder reactions

The high reactivity of the $\text{all-trans}$-1-acyloxy-1,3-pentadiene-5-ols as dienes in intramolecular Diels-Alder reactions with maleic anhydride and fumaric acid ethylester monochloride is discussed.     

Facile synthesis of quinone epoxides and 5,6-epoxy-4-hydroxy-2-cyclohexenones via the retro-diels-alder reaction

From commercially available quinoes, quinone epoxides and 5,6-epoxy-4-hydroxy-2-cyclohexenones were easily prepared through the retro-Diels-Alder reactions under rather mild conditions.     

An improved synthesis of (±)-methyl shikimate through stereoselective cis dihydroxylation of (±)-methyl 5β-hydroxycyclohexa-1,3-dienoate under prévost''s reaction conditions

A Prévost-type reaction under “wet” conditions upon the O-^tbutyl- dimethylsilyl derivative of (±)-methyl 5β-hydroxycyclohexa-1,3-dienoate gives (±)-methyl 3α-acetoxy-4β-hydroxy-5β-^tbutyldimethylsilyloxycyclohexene which may be readily deprotected to afford (±)-methyl Shikimate in very high yield. Less selectivity is observed in a similar reaction upon the parent alcohol and when this compound is reacted under dry conditions the major product is (±)-methyl 4β,5β-epoxy-3β-acetoxycyclohexenoate. An analysis of Prevost reactions with $\text{exo}$ and $\text{endo}$ methyl 7-oxabicyclo [2,2,1]hept-5-en-2-oate is also described.     

Total synthesis of slow reacting substances (SRS's): 6-epi-leukotriene C and 6-epi-leukotriene D

6-$\text{Epi}$-leukotrienes C and D (3 and 4) have been synthesized unambiguously via the 5($\text{S}$), 6($\text{R}$)-epoxide (5,6-$\text{cis}$) which is isomeric with leukotriene A. These 6-$\text{epi}$-leukotrienes are less active (especially 4) than leukotrienes C and D (1 and 2) and have not been found in substantial quantity in natural SRS sources.