Steroidal antifeedants from the dorid nudibranch Aldisasanguineacooperi

Two steroids, 3-oxo-chol-4-ene-24-oic acid ($\text{2}$) andi ts unsaturated analog $\text{4}$ have been isolated from the dorid nudibranch $\text{Aldisa}$$\text{sanguinea}$$\text{cooperi}$, and the acid $\text{2}$ has been shown to have antifeedant properties.     

The ipso-nitration of p-cresol

The nitration of $\text{p}$-cresol by nitric acid in aqueous sulphuric acid involves ~40% $\text{ipso}$-substitution at C^Me. The 4-methyl-4-nitrocyclohexa-2,5-dien-1-one (I) formed undergoes an acid-catalysed rearrangement to 4-methyl-2-nitrophenol.     

Boat-chair conformational preference of exo, exo-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid

The ¹H and ¹³C nmr spectra of $\text{exo}$, $\text{exo}$-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d₆ or alkaline D₂O, clearly show that it exists in a $\text{boat}$-$\text{chair}$-conformation with $\text{equatorial}$ carboxyl groups, thus being the first case of $\text{boat}$-$\text{chair}$ preference of a bicyclo[3.3.1] nonan-9-one due to the presence of $\text{exo}$,$\text{exo}$-2,4- substituents.     

Diastereoselective synthesis of N-acetyl-D,L-acosamine and N-benzoyl-D,L-ristosamine

N-Acyl derivatives of $\text{D}$,$\text{L}$-acosamine and $\text{D}$,$\text{L}$-ristosamine were synthesized with high stereo selectivity utilizing intramolecular Michael addition of γ- and δ-carbomoyloxy-α,β-unsaturated esters.     

Synthesis of N-benzoyl L- and D-2,3,6-trideoxy-3-aminoxylo-hexose from non-carbohydrate precursors

The enantiomeric alcohols ($\text{2}$) and ($\text{11}$), obtained from (2$\text{R}$,3$\text{R}$) tartaric acid and, respectively, $\text{L}$-threonine, have been used to construct the C₆, enantiomeric deoxy amino sugar derivatives ($\text{7}$) and ($\text{12}$)     

Rotational isomerism between the E and Z forms of o-substituted benzo-N-methyl hydroxamic acids in strong acid

The $\text{E}$∠$\text{Z}$ equilibrium of the cations of benzo hydroxamic acids, in mineral acid, was studied utilizing ¹H NMR spectroscopy, NOEDS and MNDO claculations     

Stereoselective synthesis of 1,8- and 1,5-diketo-trans-syn-trans-perhydroanthracenes

A stereOselective conversion of 1,8- and 1,5-diethoxy-9,10-anthraquinone to 1,8- and 1,5-diketo-$\text{trans}$-$\text{syn}$-$\text{trans}$-perhydroanthracenes by successive sodium borohydride, metal-ammonia, and catalytic reductions is described.     

Stereoselective synthesis of the optically active functionalized 1,3,5-all-anti-triol

The optically active 1,3,5-$\text{all}$-$\text{anti}$-triol $\text{20}$ was synthesized starting from ($\text{S}$)-(-)-malic acid with complete stereoselection, based on the stereoselective reduction of cyclic β-keto acetal and successive transthioacetalization.     

[2+2] Cycloaddition of benzyne to cis,trans- and cis,cis-1,5-cyclooctadiene

The relative rates of formation of $\text{cis}$ and $\text{trans}$ [2+2]cycloadducts of benzyne to $\text{cis}$, $\text{trans}$- and $\text{cis}$, $\text{cis}$-1,5-cyclooctadiene, $\text{trans}$- and $\text{cis}$-cyclooctene are discussed and properties of the adducts (e.g., their unusual hydrogenation) are described.     

Synthesis of di-t-alkylamines

Di-$\text{t}$-alkylamines can be synthesized efficiently by a three-step process: (1) oxidation of a $\text{t}$-alkylamine to a $\text{t}$-alkylnitroso compound with peracetic acid in ethyl acetate (2) conversion of the $\text{t}$-alkylnitroso compound to a tri-$\text{t}$-alkylhydroxylamine by successive trapping of two $\text{t}$-butyl radicals and (3) sodium naphthalide reduction to the di-$\text{t}$-alkylamine.     

Synthesis of N-benzoyl-L-ristosamine

The synthesis of N-benzoyl-$\text{L}$-ristosamine (7) from natural tartaric acid through the intermediacy of the δ-$\text{xylo}$ and γ-$\text{ribo}$ lactones (4) and (6) is reported.     

Synthesis of N-benzoyl-L-daunosamine from D-threonine

The synthesis of N-benzoyl-$\text{L}$-daunosamine (14) from the C₄$\text{threo}$ aldehyde (2b), prepared from $\text{D}$-threonine, through the intermediacy of the C₇ adduct (7a) is reported     

Stereocontrolled additions of allyltri-n-butyl-stannane to α-hydroxyaldehyde derivatives. A useful route to monoprotected erythro or threo diols.

By proper choice of Lewis acid and protecting group, the Lewis acid mediated addition of allyltri-$\text{n}$-butylstannane to the α-hydroxyaldehyde derivatives 1b and 1c can be controlled to give excellent (95:5 to > 250:1) stereoselectivity for the formation of either $\text{erythro}$ or $\text{threo}$ products.     

Highly substituted chromanols from cultures of aspergillusduricaulis

The new compounds $\text{1}$ – $\text{4}$ and $\text{8}$ have been isolated from cultures of $\text{Aspergillus}$$\text{duricaulis}$     

Preparation of halo-F-methanes via potassium fluoride-halogen cleavage of halo-F-methylphosphonium salts

Treatment of halo-$\text{F}$-methylphosphonium salts with potassium fluoride and halogen (I₂, Br₂, ICl, IBr) gives modest yields of halo-$\text{F}$-methanes. This method of preparation augments the classical Hunsdiecker approach to these materials.     

The sterepolides: new isolactaranes from stereumpurpureum

Sterepolide and dihydrosterepolide, new sesquiterpenes isolated from the fungus $\text{Stereum}$$\text{purpureum}$, are assigned structures $\text{4}$ and $\text{7}$, respectively. The assignments are based mainly on spectroscopic studies and similarities to isolactarorufin ($\text{5}$). A possible mode of biogenesis of these isolactarane type sesquiterpenes is discussed.     

New highly oxidized fusicoccane diterpenoids from the liverwort plagiochilaacanthophylla subsp. japonica

Four novel fusicoccane diterpenoids, fusicoplagins A, B, C, and D, have been isolated from the liverwort $\text{Plagiochila}$$\text{acanthophylla}$ subsp. $\text{japonica}$ and the structures determined by spectroscopic methods, chemical transformations, and X-ray crystallographic analysis.     

A new polyether toxin from Gymnodiniumbreve Davis

A new ichthyotoxic toxin was isolated from the unialgal culture of the deleterious Florida red tide organism, $\text{Gymnodinium}$$\text{breve}$ Davis (Syn. $\text{Ptychodiscus}$$\text{brevis}$), and its structure was elucidated.     

Electronic spectra of 12-S-CIS conformationally locked retinals

The electronic absorption spectra of the four new 12-$\text{s}$-$\text{cis}$-locked retinals (1a–1d) bearing 7-$\text{trans}$, 11-$\text{trans}$ double bond geometries are described and compared with those of analogous 7-$\text{trans}$, 11-$\text{cis}$-geometries (1e–1h) and parent retinals (2a-h).     

Two chrome derivatives from the brown alga Zonariatournefortii

Two minor lipid components of the brown seaweed $\text{Zonaria}$$\text{tournefortii}$ were characterized as (all Z) - 5′,7′-dihydroxy-2′-nonadeca-4,7,10,13,16-pentenyl-chrome chromone ($\text{3}$) and 5′,7′-dihydroxy-2′-pentadecylchrome ($\text{4}$).