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.     

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.     

The isoindolobenzazepine alkaloids

Three Chilean barberries, $\text{Berberis}$$\text{actinacantha}$ Mart. ex Schult., $\text{B}$. $\text{darwinii}$ Hook and [ulbar|B. $\text{valdiviana}$Phil. (Berberidaceae), have yielded several new isoindolobenzazepine and protoberberine alkaloids. Novel isoindolobenzazepines are (±)-13-deoxychilenine ($\text{a}$), pictonamine ($\text{10}$), chileninone ($\text{12}$), (±)-chileniimi ($\text{18}$) and (±)-palmanine ($\text{19}$). Highly oxidized protoberberines of particular interest include (±)-O-methylprechilenine ($\text{6}$) and (±)-prepseudopalmanine ($\text{21}$), together with 13-methoxy-8-oxyberberine ($\text{8}$). Isoindolobenzazepine alkaloids arise biogenetically from the rearrangement of highly oxidized protoberberines.     

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 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.     

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 $\text{3}$.     

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.     

Complementary short syntheses of (±)-methyl shikimate

Two syntheses of (±)-methyl shikimate from the adduct of furan and methyl acrylate are described. One requires the regioselective hydroxylation of (±)-5β,6β-dihydroxy-$\text{O}$,$\text{O}$-isopropylidene-2-methoxycarbonylcyclohexa-1,3-diene and the other $\text{cis}$-dihydroxylation of (±)-5-hydroxy-1-methoxycarbonylcyclohexa-1,3-diene.     

Synthesis and absolute configuration of +-lineatin,the pheromone of trypodendronlineatum

A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.0^4,7] nonane, $\text{1}$) was achieved. The stereochemistry of (+)-lineatin was established as 1$\text{R}$, 4$\text{S}$, 5$\text{R}$, 7$\text{R}$ by an X-ray crystallographic analysis of an intermediate $\text{1}$$\text{5}$.     

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.     

Synthetic photochemistry. Synthesis of (±)oliveroline and (±)ushinsunine

Sodium borohydride reduction of 1-(2′-Bromobenzoyl)-2-methyl-3,4-dihydro-6,7-methylenedioxyisoquinolinium iodide ($\text{4}$) gave a mixture of alcohols which on irradiation in dil.HCl afforded (±) oliveroline and (±)ushinsunine.     

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.     

Synthesis of (±)-ascochlorin,an antiviral antibiotic

(±)-Ascochlorin, 5-chloro-2, 4-dihydroxy-6-methyl-3-[(2$\text{E}$, 4$\text{E}$)-5-(1,2,6-trimethyl-3-oxocyclohexyl)3-methyl-3,4-pentadienyl] benzaldehyde, was synthesized in 14 steps from (±)-3,4-dimethyl-2-cyclohexenone.     

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.     

The total synthesis of 1-oxygenated eudesmane sesquiterpenes : (±) dihydroreynosin and (±) 1-oxocostic acid

The total synthesis of (±) dihydroreynosin $\text{1}$ and of (±) 1-oxocostic acid $\text{2}$ (R = H) are illustrative examples for a short entry into 1-oxygenated eudesmanes via an easily accessible key intermediate $\text{7}$.     

The crystal structures of α- and β-CdUO4

The structural parameters of α- and β-CdUO₄ crystals are determined by X-ray powder diffraction technique. α-CdUO₄ is rhombohedral and cell parameters are a = 6.233(3) Å and α = 36.12(5)°. β-CdUO₄ crystallizes in a C-centered orthorhombic cell with a = 7.023(4), b = 6.849(3), c = 3.514 (2) Å. The space groups are $\text{R}\text{3}\text{m}$ for α-CdUO₄ and Cmmm for β-CdUO₄. α-CdUO₄: 1U in (000), 1Cd in ($\text{1}\text{2}\text{1}\text{2}\text{1}\text{2}$), 2O(1) in ±(uuu), 2O(2) in ±(vvv); u = 0.113, v = 0.350, Z = 1. β-CdUO₄: 2U in ($\text{000;}\text{1}\text{2}\text{1}\text{2}\text{0}$), 2Cd in ($\text{1}\text{2}\text{0}\text{1}\text{2}\text{; 0}\text{1}\text{2}\text{,}\text{1}\text{2}$), 4O(1) in ($\text{0, ±y, 0;}\text{1}\text{2}\text{,}\text{1}\text{2}\text{±y, 0}$), 4O(2) in ($\text{±x, 0,}\text{1}\text{2}\text{;}\text{1}\text{2}\text{±x,}\text{1}\text{2}\text{,}\text{1}\text{2}$); x = 0.159, y = 0.278, Z = 2. β-CdUO₄ contains collinear uranyl UO²⁺₂ groups with a UO(1) distance of 1.91 Å, located either along or parallel to the c axis whereas the UO(1) bond length in α-CdUO₄ is 1.98 Å which is longer than the usual uranyl bond length.     

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.     

Total synthesis of (±)-podophyllotoxin and (±)-epipodophyllotoxin.

A novel approach to (±)-epipodophyllotoxin ($\text{2}$) and hence also (±)-podophyllotoxin ($\text{1}$) is described, involving as a key-step the stereoselective ring closure of the TMS-ester derived from $\text{14a}$ to the tetralin derivative $\text{15}$ with mesyl chloride.     

Biogenetic-type synthesis of (±)-dictyopterene A,an odoriferous substance obtained from brown seaweeds, Dictyopteris

Biogenetic-type synthesis of (±)-dictyopterene A ($\text{1}$) was achieved employing 1,$\text{cis}$-5-undecadien-3-ol ($\text{2}$) postulated to be a biosynthetic intermediate of $\text{1}$: this synthesis means that transformation of dictyoprolene ($\text{4}$) into dictyopterene A ($\text{1}$) was formally made.     

Formal total synthesis of β-pipitzol

(±)-$\text{O}$-methylperezone ($\text{1b}$) was obtained by selective oxidative demethylation of (±)-leucoperezone trimethyl ether ($\text{4a}$). Compound ($\text{4a}$) was prepared by condensation of 2,3,5-trimethoxytoluene ($\text{5e}$) with 6-methyl-5-hepten-2-one, followed by reductive removal of the tertiary alcohol. The aromatic precursor $\text{5e}$ was prepared in four steps from 2,3-dimethoxytoluene ($\text{5a}$) and, alternatively, in three steps from 5-bromoveratraldehyde ($\text{6a}$). Racemic $\text{1b}$ and $\text{4a}$ were directly compared with the optically active molecules prepared from natural R(-)-perezone ($\text{1a}$).