A convenient synthesis of flindersine,atanine and their analogues

A new synthesis of the pyranoquinolone alkaloids flindersine ($\text{8a}$), 8-methoxyflindersine ($\text{8c}$), N-methylflindersine ($\text{9a}$), zanthobunglanine ($\text{9c}$) oricine ($\text{9d}$) and veprisine ($\text{9e}$) and the prenylquinolone alkaloids atanine ($\text{13a}$), preskimmianine ($\text{13e}$) N-methylatanine ($\text{14a}$), O-methylglycosolone ($\text{14c}$) and N-methylpreskimmianine ($\text{14e}$) is described.     

Synthesis of 2-isopropylfuro(2,3-b)quinolines-a new synthesis of (±)-lunacrine, (±)-lunasine and (±)-demethoxylunacrine

A new and convenient synthesis of 2-isopropylfuro-(2,3-b)quinolines ($\text{4}$) from 3-(3-methylbut-1-enyl)-2-quinolones ($\text{2}$) is described. A neat synthesis of the alkaloids (±)-lunacrine ($\text{1a}$), (±)-lunasine ($\text{12a}$) and (±)-demethoxylunacrine ($\text{1b}$) is also reported.     

The total synthesis of i-oxygenated eudesmanolides

A route towards I-oxygenated eudesmanolides, via a (2+2) photocycloaddition reaction for constructing the decalin framework is described. The following natural substances have been synthesized. (=)-dihydroreynosin ($\text{1}$), (±)-1- oxo-dihydronmagnolialide ($\text{2}$), (±)-maritimin ($\text{3}$), (±)-dihydromagnolialide ($\text{4}$), (±)-magnolialide ($\text{5}$), (±)-dihydrosantamarine ($\text{6}$). Also a synthesis of (±)--santonin ($\text{7}$) is presented.     

Total syntheses of (±)-isoagatholactone and (±)-12α-hydroxyspongia-13(16),14-dien

(±)-Isoagatholactone $\text{1}$ and (±)-12α-hydroxyspongia-13(16),14-dien $\text{2b}$, a fundamental skeleton of spongiadiol $\text{2a}$ and its congeners, have been synthesized from (±)-labda-8(20),13-dien-15-oic acid $\text{3}$.     

Total synthesis of (±)-Lycodine

(±)-Lycodine ($\text{1}$) has been synthesized in five steps from cyanoenone $\text{4}$. The approach has also been applied to a new synthesis of (±)-lycopodine ($\text{2}$). Both alkaloids are available in better than 20% overall yield from enone $\text{4}$.     

The total synthesis of (±)-colorata-4(13), 8-dienolide

The total synthesis of (±)-colorata-4(13),8-dienolide ($\text{1}$), a sesquiterpene with a rearranged drimane skieleton, is described using 6β, 8aβ-dimethyl-5-methylene-3,4,4aα, 5,6,7,8,8a-octahydro-1(2H)-naphtalenone ($\text{10}$) as a key intermediate. A new annelation method for butenolides via hydrolysis of a thiohenyl furan is reported.     

An intramolecular diels-alder approach to quassinoids—a stereoselective construction of a-aromatic klaineanone

Thermolysis of a benzocyclobutene derivative ($\text{20}$) prepared from norcamphor produced stereoselectively a tetracyclic compound ($\text{2}$), which was converted to a lactone ($\text{21}$) having correct stereochemistry at C₇, C₈, C₉, C₁₁, C₁₃, and C₁₄ positions of (±)-klaineanone.     

Novel benzopyridoquinolizine bases from alangiumlamarckii Thw.

Alangimarine ($\text{1}$), alamarine ($\text{2}$) and alangimaridine ($\text{3}$), isolated from the seeds of the title plant, have been characterised as a new class of alkaloids. Presence of isoalamarine ($\text{13}$) in the stem-bark is indicated.     

A facile synthesis of (±)-sesbanine via γ-addition of ketene silyl acetal with quaternized methyl nicotinate

Total synthesis of (±)-sesbanine ($\text{1}$) was carried out using γ-addition of ketene silyl acetal of methyl 3-cyclopentenecarboxylate to quaternized methyl nicotinate. The resulting 1,4-dihydropyridine ($\text{7}$) was oxidized with DDQ to give 4-substituted nicotinate ($\text{2}$) and $\text{2}$ was converted to alcohol ($\text{8}$) by stereoselective oxymercuration followed by treatment with ammonia to give $\text{1}$.     

1,6-dihydro-3(2H)-pyridinones as synthetic intermediates. A novel total synthesis of (±)-ibogamine and (±)-epiibogamine

A new synthesis of (±)-ibogamine ($\text{4}$) and (±)-epiibogamine ($\text{5}$), involving the intramolecular Michael addition of the keto unsaturated ester ($\text{11}$), is described.     

Stereoselective total syntheses of (±)-warburganal and (±)-isotadeonal

A short, stereoselective synthesis of (±)-warburganal ($\text{1}$), its C-9 epimer ($\text{2}$) and the related sesquiterpene dialdehyde (±)-isotadeonal is presented.     

Total synthesis of (±)-xanthocidin and (±)-desdihydroxy-4,5-dihydroxanthocidin

The first total synthesis of both (±)-xanthocidin ($\text{1}$), a novel α-methylene cyolopentanoid antibiotic, and (±)-desdihydroxy-4,5-dihydpoxanthocidin ($\text{2}$), the likely penultimate biosynthetic precursor is reported.     

A reinvestigation of the structures of acomonine,iliensine, 14-dehydroiliensine,and 14-benzoyliliensine

The novel structures assigned by Yunusov et al to the C₁₉-diterpenoid alkaloids, acomonine ($\text{1}$), iliensine ($\text{2}$), 14-dehydroiliensine ($\text{3}$), and 14-bensoyliliensine ($\text{4}$) have been found to be in error. We have demonstrated that these alkaloids are identical with the well-known alkaloids, delsoline ($\text{5}$), delcosine ($\text{6}$), 14-dehydrodeloosine ($\text{7}$), and 14-benzoyldelcosine ($\text{8}$), respectively.     

The quettamines: a new class of isoquinoline alkaloids

Three quettamine type alkaloids, which incorporate either a benzofuran or a dihydrobenzofuran moiety within the molecular framework, have been obtained from $\text{Berberis}$$\text{baluchistanica}$. These are dihydrosecoquettamine ($\text{1}$), secoquettamine ($\text{2}$), and quettamine chloride ($\text{3}$). Alkaloids $\text{1}$ and $\text{3}$ are racemates. Hofmann degradation of quettamine ($\text{3}$) provides secoquettamine ($\text{2}$) and the styrene $\text{4}$ which has a trans relationship between the hydrogens at C-1 and C-α, thus indicating the identical stereochemistry in quettamine. Emde reduction of quettamine leads to dihydrosecoquettamine ($\text{1}$) and the stilbene $\text{5}$. Two other polar alkaloids in the plant are (+)-armepavine methochloride ($\text{6}$) and oblongine chloride ($\text{7}$). An oblongine type alkaloid must be the biogenetic precursor for the quettamines. Arguments are presented favoring direct oxidative coupling in the biogenesis of the cularine alkaloids.     

Chilenine: An isoindolobenzazepine alkaloid

(±)-Chilenine ($\text{3}$), the first isoindolobenzazepine alkaloid, has been found in $\text{Berberis}$$\text{empetrifolia}$ Lam. (Berberidaceae).     

Stereoselective total syntheses of (±)-sinularene and of (±)-5-epi-sinularene via intramolecular type-I-“magnesium-ene” reaction

(±)-Sinularene ($\text{1}$) as well as (±)-5-epi-sinularene ($\text{9}$) were synthesised in a stereocontrolled manner from the norbornene $\text{2}$ in overall yields of 4% and 8%, respectively. The key step $\text{5}$ → $\text{6}$ involves a regio- and stereoselective intramolecular “magnesium-ene” reaction.     

Biosynthetic pathway of iridoid glucosides in Gardenia jasminoides f. grandiflora cell suspension cultures after iridodial cation formation

Administration of ²H- or ¹³C-labeled monoterpenes to $\text{Gardenia}$$\text{jasminoides}$ f. $\text{grandiflora}$ cell suspension cultures demonstrated that iridoid glucosides of the suspension cultures are biosynthesized, after iridodial cation formation from 10-oxocitral (3), via 8-epiiridodial (13), 8-epiiridotrial (14), boschnaloside (8-epiiridotrial glucoside) (12) and dehydroiridotrial glucoside (8). In addition, the coexistence of a route via iridodial cation (4), dehydroiridodial (6), dehydroiridotrial (15) and dehydroiridotrial glucoside (8) is conceivable.     

A total synthesis of (±)faranal,the true trail pheromone of pharaoh's ant, monomorium pharaonis

A relatively brief total synthesis of (±)-Faranal [3$\text{SR}$,4$\text{RS}$), (6$\text{E}$,1O$\text{Z}$)-3,4,7, 11-tetramethyl-6,10-tridecadien-l-al] (1) is reported.     

Fluorescence quantum yields and cascade-free lifetimes of state selected CO+2, COS+, CS+2 and N2O+ determined by photoelectron—photon coincidence spectroscopy

The details and principles of an apparatus built for measurements of fluorescence quantum yields and cascade-free lifetimes of open-shell cations are reported. These rely on the detection of coincidences between energy selected photoelectrons and undispersed photons. The results of such measurements for CO⁺₂, COS⁺, CS⁺₂ and N₂O⁺ in selected vibrational levels of their excited states are presented. Non-unity fluorescence quantum yields are found for some vibronic levels of CO⁺₂($\text{B}$), COS⁺ ($\text{A}$), N₂OP⁺($\text{A}$) and a non-exponential decay is observed for CS⁺₂($\text{A}$). The data yield the following values for the radiative lifetimes: CO⁺₂($\text{A}$) 124 ± 6 ns, CO⁺₂($\text{B}$) 140 ± 7 ns, COS⁺($\text{A}$) 550 ± 50 ns and N₂O⁺($\text{A}$) 240 ± 12 ns.     

A total synthesis of leukotriene F4 (LTF4)

The synthesis of LTF₄ via the reaction of (±)-leukotriene A₄(LTA₄), methyl ester $\text{1}$ with the protected gluramylcysteine $\text{2}$ is reported.