Renierone,an antimicrobial metabolite from a marine sponge

The major antibacterial metabolite in the sponge $\text{Reniera}$ sp. was shown to be an isoquinoline quinone, renierone ($\text{1}$). The structure of renierone ($\text{1}$) was defined by X-ray crystallography.     

Stereoselective synthesis of (25R)-25,26-dihydroxy-23-oxovitamin D3 and its enzymatic conversion to (25R)-1α,25,26-trihydroxy-23-oxovitamin D3, a putative metabolite of vitamin D3

(25$\text{R}$)-25,26-Dihydroxy-23-oxovitamin D₃ was synthesized efficiently and stereoselectively, and it was converted enzymatically to (25$\text{R}$)-1α,25,26-trihydroxy-23-oxovitamin D₃, a putative metabolite of 1α,25-dihydroxyvitamin D₃. The spectral and chemical properties of (25$\text{R}$)-25,26-dihydroxy-23-oxovitamin D₃ and its 1α,hydroxylated derivative disagree with those reported for the isolated metabolite.     

Structure and synthesis of reductiline,a novel metabolite from a variant of streptomyces orientalis

The structure of reductiline, a metabolite of a variant of $\text{Streptomyces orientalis}$ was elucidated as ($\text{1}$) based on chemical and spectroscopic evidence. Transformation of an antitumor antibiotic reductiomycin ($\text{2}$) into reductiline ($\text{1}$) was carried out. Synthesis of reductiline ($\text{1}$) was achieved starting from β-cyanopropionaldehyde dimethylacetal.     

Studies on highly oxidized cyclohexanes. Constitution of a new key metabolic intermediate.

The absolute stereostructure of (?)1,6 desoxypipoxide ($\text{2}$), a new plant metabolite of biosynthetic significance was assigned by spectral interpretation and chemical correlation with (+)pipoxide ($\text{1}$).     

Conversion of adenosine to a pentacyclic structure by a 4-nitroquinoline-1-oxide metabolite model.

A new pentacyclic compound $\text{2A}$ has been obtained from the reaction of adenosine $\text{1}$ with 1-acetoxy-4-(acetoxyimino)-1,4-dihydroquinoline $\text{3}$, a model for the ultimate metabolite of the carcinogen 4-nitroquinoline-1-oxide. 9-propyladenine $\text{5}$ gives an analogous pentacyclic product $\text{6A}$ whose crystal structure has been determined.     

Sirodesmin A: Synthesis of a chiral left half.

A stereoselective and chiral synthesis of a precursor to the fungal metabolite sirodesin A ($\text{1}$) is described. The correct relative and absolute confirugation for intermediate $\text{3}$ (Scheme 1) is established in a single, highly enantioselective epoxidation.     

Balearone,a metabolite of the brown alga cystoseirabalearica

The isolation of a new metabolite of mixed biogenesis, balearone $\text{1}$from the brown alga $\text{Cystoscira}$$\text{balearica}$ is described. The structure was determined by an X-ray diffraction analysis.     

Chiral synthesis of (2s,3s,7s)-3,7-dimethylpentadecan-2-yl acetate and propionate,potential sex pheromone components of the pine saw-fly neodiprion sertifer (geoff.)

A synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate ($\text{2}$) and propionate ($\text{3}$) is described. (2S)-2-Methyldecan-1-yl lithium ($\text{5}$) was reacted with (3S,4S)-3,4-dimethyl-γ-butyrolactone ($\text{6}$) to yield the ketoalcohol $\text{19}$ which upon Huang-Minlon reduction furnished (2S,3S,7S)-3,7-dimethylpentadecan-2-ol ($\text{1}$). Acylations gave the esters $\text{2}$ and $\text{3}$. The (2S)-2-methyldecan-1-yl lithium was obtained via asymmetric synthesis. The chiral lactone $\text{6}$ was obtained from (2S,3S)-trans-2,3-epoxybutane and dimethyl malonate.     

Structure elucidation and synthesis of (2s)-4-oxo-1-azabicyclo[3.3.0]octa-5,7-diehe-2-carboxylic acid,a new metabolite isolated ercm stheptomyces oliyacbjs

The structure of a new metabolite isolated from $\text{Streptomyces}$$\text{olivaceus}$ has been shown to be (2S)-4-oxo-1-azabicyclo[3.3.0]octa-5,7-diene-2-carboxylic acid by means of its spectroscopic properties and total synthesis.     

Oxidation of N-hydroxyazetidines: A novel synthesis of N-acetoxy β-Lactams and four-membered cyclic nitrones

The N-hydroxyazetidines $\text{2}$ and $\text{3}$ are prepared startinfrom 2,3-dihydroazete 1-oxides ($\text{1a}$ and $\text{1b}$0 by reduction with sodium borohydride and by reaction with a nucleophile, respectively. The N-thydroxyazetidines $\text{2}$ and $\text{3}$ can be oxidized with mercury (II) oxide to the corresponding nitrones $\text{1}$; oxidation of the N-hydroxyazetidine $\text{2a}$ (unsubstituted at C-4) with $\text{two}$ equivalent of lead tetraacetate tyields the N-tacetoxy β-lactam $\text{4}$.     

Structure of sclerosporin,a sporogenic substance of sclerotiniafructicola

Sclerosporin, the major sporogenic substance of $\text{S. fructicola}$, and its related metabolite, sclerosporal, were shown to have the plain structures, $\text{1}$, and $\text{2}$, respectively. by using a micro-amount of the samples, and co-occurring sclerosporene probably to have the structure $\text{3}$.     

The structure of paraherquamide,a toxic metabolite from penicilliumparaherquei

A new toxic metabolite was isolated from $\text{Penicillium}$$\text{paraherquei}$ and the structure was determined by X-ray diffraction analysis. The metabolite was designated as paraherquamide.     

Microwave-optical double resonance in molecular ions. Co+

Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for ¹²C¹⁶O⁺. With the optical excitation of fluorescence from the R₁ ($\text{1}\text{2}$) line of the (0,0) band of the A²Π_{$\text{3}\text{2}$} ← X²∑ transition of 20350.6 cm^?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = $\text{3}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ and the N = 1, J = $\text{1}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ transitions.     

A short and efficient synthesis of 4-hydroxy-5-(1-hydroxyalkyl)-γ-butyrolactones

The cycloaddition of α,β-epoxyaldehydes or ketones ($\text{2}$) with the ketene acetal MeHC=C(OMe)₂ ($\text{1}$) gives epoxyoxetanes ($\text{3}$) in high yields. Without isolation they can be transformed into 4-hydroxy-5-(1-hydroxyalkyl)-γ-butyrolactones ($\text{6}$) via the epoxy esters $\text{4}$ and trihydroxy esters ($\text{5}$). The lactones $\text{6}$ appear to be valuable precursors for the synthesis of 5-(1-hydroxyalkyl)-3-methyl-2-5H-furanones ($\text{7}$) and 3-methyl-5-ylidene-2-5H-furanones ($\text{8}$)     

Action of tert-butyl azidoformate on the conjugate bases of 1,2,3,4-tetrahydro-9H-carbazole and other indole derivatives

tert-Butyl azidoformate ($\text{2}$) reacts with the conjugate bases of $\text{3a}$, $\text{7a}$, $\text{9}$ (R¹ = R² = CH₃), and $\text{9}$ (R¹ = CH₃, R² = H) to give products [$\text{4}$, $\text{8}$, $\text{12}$, and $\text{14}$, respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives.     

Inflatene,an ichthyotoxic c12 hydrocarbon from the stoloniferan soft coral clavularia inflata var. luzoniana

A new tricyclic C₁₂ hydrocarbon, inflatene (1), possessing unexpected ichthyotoxic properties, has been isolated as the major metabolite of the stoloniferan $\text{Clavularia inflata}$ var. $\text{luzoniana}$. The structure of inflatene was secured by extensive FT-NMR studies with the natural product and several key derivatives.     

Structure of HC-toxin,a cyclic tetrapeptide from helminthosporium carbonum

$\text{Helminthosporium carbonum}$, which is pathogenic to maize, produces a metabolite, HC-toxin ($\text{1}$), with selective toxicity to susceptible host genotypes. Resistant genotypes and non host plants are tolerant. The structure of $\text{1}$ (C₂₁H₃₂N₄O₆) was determined as cyclo [(2-amino-9,10-epoxy-8-oxodecanoyl)-alanyl-alanyl-prolyl] based upon spectral evidence.     

New synthesis of benzo [a]quinolizidin-2-ones via protected 2-aryl-4-piperidones

A new synthesis of 9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-benzo aquinolizin-2-one ($\text{1a}$ and its 3-ethyl derivative $\text{1b}$ via the corresponding 2-(3,4-dimethoxyphenyl)-4-piperidone ethylene acetals $\text{7}$ is reported. Alkylation of 2-arylpipendires $\text{7}$ with 2-bromoethanol followed by oxidation of the resulting amino alcohols $\text{9}$ with oxalyl chloride and dimethyl sulfoxide afforded the aldehydes $\text{10}$, which were cyclized with hydrochloric acid to give 7-hydroxybenzo[α]quinolizidines $\text{11}$. The reduction of $\text{1}$ with trinethylsilane and subsequent acid hydrolysis led to benzo aquinolizidin-2-ones $\text{1}$.     

Marine natural products: fistularin-1, -2 and -3 from the sponge Aplysina fistularis forma fulva

Three new high molecular weight bromotyrosine-related metabolites, $\text{3a}$, $\text{4a}$ and $\text{5a}$, were isolated from the sponge Aplysina ( Verongia) fistularis forma fulva, and their structures were determined from high resolution ¹H NMR and other spectroscopic data. The new metabolites are formally derived by combination of major segments of two known Aplysina metabolites $\text{1a}$ and $\text{2}$.