2430-93-5

The ring-opening of gem-difluorocyclopropyl acetaldehydes producing selectively (E,E)- and (E,Z)-conjugated fluorodienals is described. Two stereo-divergent methods are presented to access both stereoisomers from a common precursor, in high yield and selectivity. The mechanistic aspect of these transformations is discussed.

Chiral electrophilic selenium catalysts have been applied to catalytic asymmetric transformations of alkenes over the past two decades. However, highly enantioselective reactions with a broad substrate scope have not yet been developed. We report the first successful example of this reaction employing a catalyst based on a rigid indanol scaffold, which can be easily synthesized from a commercially available indanone. The reaction efficiently converts β,γ-unsaturated carboxylic acids into various enantioenriched γ-butenolides under mild conditions.

Carboxylate anions, dianions and ester enolates provide simultaneous protection and activation for directed carbometalation reactions. Advantage can be taken of the bis-carbanionic character of the intermediate for further controlled C-C bond forming reac

Merging is the game! The coupling of a domino reaction and an internal neutral redox reaction constitutes an excellent manifold for the stereoselective synthesis of di- and trisubstituted olefins featuring a malonate unit, an ester, or a free carboxylic acid as substituents at the allylic position (see scheme; MW=microwave). The reaction utilizes simple starting materials (propargyl vinyl ethers), methanol or water as solvents, and a very simple and bench-friendly protocol. Copyright

Synthesis of (E)-β,-γunsaturated acids from aldehydes with malonic acid has been explored under solvent-free conditions. The modified Knoevenagel condensation reaction with N-methyl morpholine (NMM) as catalyst exhibits highly β,-γ regioselectivity and exclusively E-stereoselectivity. A mechanism accounting for both regio- and stereoselectivity has been proposed and preliminarily studied. Copyright Taylor & Francis Group, LLC.

Epoxides of fatty acids are hydrolyzed by epoxide hydrolases (EHs) into dihydroxy fatty acids which are of particular interest in the mammalian leukotriene pathway. In the present report, the analysis of the configuration of dihydroxy fatty acids via their respective hydroxylactones is described. In addition, the biotransformation of (±)-erythro-7,8- and -3,4-dihydroxy fatty acids in the yeast Saccharomyces cerevisiae was characterized by GC/EI-MS analysis. Biotransformation of chemically synthesized (±)-erythro-7,8- dihydroxy(7,8-2H2)tetradecanoic acid ((±)-erythro- 1) in the yeast S. cerevisiae resulted in the formation of 5,6-dihydroxy(5,6- 2H2)dodecanoic acid (6), which was lactonized into (5S,6R)-6-hydroxy(5,6-2H2)dodecano-5-lactone ((5S,6R)-4) with 86% ee and into erythro-5-hydroxy(5,6-2H2)dodecano-6- lactone (erythro-8). Additionally, the α-ketols 7-hydroxy-8-oxo(7- 2H1)tetradecanoic acid (9a) and 8-hydroxy-7-oxo(8- 2H1)tetradecanoic acid (9b) were detected as intermediates. Further metabolism of 6 led to 3,4-dihydroxy(3,4- 2H2)decanoic acid (2) which was lactonized into 3-hydroxy(3,4-2H2)decano-4-lactone (5) with (3R,4S)-5=88% ee. Chemical synthesis and incubation of (±)-erythro-3,4-dihydroxy(3,4- 2H2)decanoic acid ((±)-erythro-2) in yeast led to (3S,4R)-5 with 10% ee. No decano-4-lactone was formed from the precursors 1 or 2 by yeast. The enantiomers (3S,4R)- and (3R,4S)-3,4-dihydroxy(3- 2H1)nonanoic acid ((3S,4R)- and (3R,4S)-3) were chemically synthesized and comparably degraded by yeast without formation of nonano-4-lactone. The major products of the transformation of (3S,4R)- and (3R,4S)-3 were (3S,4R)- and (3R,4S)-3-hydroxy(3-2H 1)nonano-4-lactones ((3S,4R)- and (3R,4S)-7), respectively. The enantiomers of the hydroxylactones 4, 5, and 7 were chemically synthesized and their GC-elution sequence on Lipodex E chiral phase was determined.

The total synthesis of (+/-)-cascarillic acid has been achieved by a sequential cross-metathesis/Simmons-Smith cyclopropanation between, respectively, 1-octene with an appropriate unsaturated carboxylic acid. In parallel, a direct access to grenadamide was developed from 1-nonene with a readily available unsaturated amide. In both cases, the chemical yields were high (up to 98%) and the E/Z ratio was near 80/20. The synthesis of a dibromocyclopropane analogue has also been considered.

Reaction of the lithium α-sulfinyl carbanion of chloromethyl phenyl sulfoxide with α,β-alkenyl carboxylic acid chlorides gave γ,δ-alkenyl α-chloro-β-keto sulfoxides in variable yields. The keto sulfoxides were also synthesized from α,β-alkenyl aldehydes in two steps in good overall yields: addition of the lithium α-sulfinyl carbanion of chloromethyl phenyl sulfoxide to α,β-alkenyl aldehydes followed by oxidation of the adducts with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or Dess-Martin periodinane. These products were treated in sequence with potassium hydride, tert-butyllithium, and 5% aqueous sodium hydroxide, in one flask to give β,γ-alkenyl carboxylic acids with one-carbon elongation in good yields. The procedure offers a new method for synthesizing β,γ-alkenyl carboxylic acids from α,β-alkenyl carboxylic acid chlorides and α,β-alkenyl aldehydes with one-carbon elongation.

Aliphatic aldehydes with α-hydrogens and malonic acid undergo decarboxylative condensation on the surface of SiO2 when subjected to microwave irradiation generating βγ-unsaturated acids in high yields.

(E)-Alk-3-enoic acids have been prepared in high yield (85-90%) and excellent stereoselectivity (98-99%) by a modified Knoevenagel condensation of a straight carbon chain aldehyde with malonic acid, in dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) at 100°C, in the presence of piperidinium acetate as catalyst. Condensation of the aldehyde with a monoester of malonic acid, under the above conditions, gave the corresponding ester of (E)-alk-3-enoic acid in high yield (76-82%) and good stereoselectivity (90-92%). Condensation of the aldehyde with cyanoacetic acid gave the β,γ-unsaturated nitrile in moderate yield (35-40%) without stereoselectivity.

A combination of the Horner-Emmons synthesis of alkyl 2,4-dienoates with their hydrogenation over complex L·Cr(CO)3 catalysts (L = 3CO or arene) provides a versatile, stereocontrolled and operationally simple approach to the (Z)-disubstituted, (Z)-trisubstituted, (E)-trisubstituted alkenes and skipped (Z,Z)-disubstituted diolefins with a homoallylic type of function. This protocol, sometimes supplemented by an enzymatic hydrolysis, was successfully applied to the synthesis of configurationally pure (gp ≥ 98%) pheromones of the furniture carpet beetle, dry bean beetle, rusty grain beetle, square-necked grain beetle and of a trail-following pheromone mimic for subterranean termites

On the basis of a modified Knoevenagel reaction starting from octanal and decanal, the stereodirected synthesis has been effected of dodec-5E-en-ol (the pheromone of the grass fly Tricimba cincta - and tetradec-5E-en-yl acetate) an imitator of the pheromone of the moth Rhynchopacha sp.

The reduction of sodium salts of 2,4-alkadienoic acids bearing alkyl substituents in the different positions of the diene system, in aqueous solution with sodium dithionite, affords E:Z isomeric mixtures of 3-alkenoic acids after acidification.These results are compared with those reported with those reported for the related reaction under phase transfer catalysis of the corresponding alkyl alkadienoates.Formation of sulfinic adducts as intermediates in the reduction of sorbic acid points to a two stage mechanism for the overall reduction process.

This invention relates to a compound of the formula: STR1 or a pharmaceutically acceptable salt thereof wherein X is oxygen, sulfur, or --CH=CH--; wherein Z is OR1 or --NR4 R5 ; wherein R1 is hydrogen, lower alkyl, or a pharmaceutically acceptable cation; wherein R2 is H, --CH3 or --C2 H5 ; wherein R3 is OH, H or =O; wherein R4 and R5 may independently be hydrogen, or lower alkyl having 1-6 carbon atoms, or R4 and R5 may act together with N to form a cyclic amide of the formula: STR2 wherein n is an integer from 4-5; and m is an integer from 0-4. More particularly, this invention relates to compounds of the above formula which have utility as LTB4 antagonists.

Condensation of aliphatic aldehydes with a three molar excess of malonic acid and 0.001 mole piperidinium acetate in refluxing xylene, with continuous removal of the water formed, gave almost exclusively (E)-3-alkenoic acids, in good yield (60-85percent) and of high stereochemical purity (95-99percent).

A systematic investigation has been carried out into the effect of different reaction parameters on the oxidation of oct-1-ene by manganese(III) acetate in acetic acid and acetic anhydride.The most important factor in dictating the ratio of products is the composition of the solvent.In the absence of anhydride γ-decanolactone is virtually the sole product.Even small quantitites of anhydride lead to the lactone being replaced by other products derived from cationic intermediates C6H13CH(1+)CH2COX (X = OH or OAc).Further increases in the amount of anhydride encourage the formation of decanoic acid until, in 90percent anhydride, this becomes the predominant product.The results cannot be interpreted simply in terms of competition for the alkene by the radicals (.)CH2CO2H and (.)CH2COOCOCH3.Decanoic acid formation is also favoured by low temperatures, low concentration of oxidants, and by the addition of acetate ions.A comparision is made of the efficiency of addition when the initiating species is manganese(III) or a peroxide.

Reduction of 2,4-alkadienoic acids and esters with sodium dithionite was carried out in aqueous solution or under PTC conditions to give, almost excusively, Z:E isomeric mixtures of the corresponding 3-alkenoic acids and esters, respectively, in good yields.