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A concise enantioselective total synthesis of the neoclerodane diterpene (−)‐salvinorin A is reported. The stereogenic center at C‐12 was installed by catalytic asymmetric propargylation with excellent enantioselectivity, and the remaining six stereogenic centers were set up highly diastereoselectively under substrate control. As for our previous synthesis of racemic salvinorin A, two intramolecular Diels‐Alder reactions were applied to generate the tricyclic core. A chemoselective Mitsunobu inversion of a syn 1,2‐diol allowed for further streamlining of the original reaction sequence by two steps. Overall, (−)‐salvinorin A was synthesized in only 16 steps starting from 3‐furaldehyde with 1.4 % total yield. Furthermore, an alternative intramolecular Diels‐Alder strategy employing a 2‐bromo‐1,3‐diene moiety was investigated., A divine sage: The potent KOR agonist (−)‐salvinorin A was synthesized in only sixteen steps by modification of our previous route to the racemic title compound. Transition to asymmetric synthesis succeeded by a highly enantioselective propargylation to install the stereogenic center at C‐12. Shortening of the original reaction sequence by two steps was finally achieved using a chemoselective Mitsunobu esterification of a cyclic syn 1,2‐diol. Furthermore, an alternative intramolecular Diels‐Alder strategy employing a 2‐bromo‐1,3‐diene moiety was investigated.

The hydroazulene core of the bioactive sesquiterpenoid (-)-dehydrocostus lactone was generated by domino enediyne metathesis. A triple hydroboration/oxidation of the resultant conjugated triene installed three out of four stereogenic centers of the target in a single step. The enantiopure acyclic metathesis substrate was readily available by an asymmetric anti aldol reaction. Masking of the γ-lactone as an acetal allowed for an efficient completion of the synthesis through late-stage double carbonyl olefination.

(−)-Isoguaiene was prepared from (S)-citronellal in only 9–10 steps with good overall yields. Either a trienyne or a dienediyne metathesis and highly diastereoselective organocatalytic Michael additions of aldehydes derived from (S)-citronellal served as the key transformations.

Using an intramolecular nitrone cycloaddition and a Heck cyclization as the crucial transformations, a total synthesis of the racemic morphine alkaloid thebainone A was accomplished in 22 steps commencing with isovanillin.

1-Arylazo-substituted 2-naphthylamines, which are easily obtainable by the coupling of arene diazonium salts with 2-aminonaphthalene-sulfonic acid, can be transformed by reaction with reactive carboxylic acid derivatives or nitrosation reagents into novel 2-aryl-substituted naphtho[2,1-e][1,2,4]triazinium and naphtho[2,1-e][1,2,3,4]tetrazinium salts, respectively.

A concise and highly enantioselective synthesis of structurally diverse isoflavans from a single chromone is described. The key transformation is a single-step conversion of racemic isoflavanones into virtually enantiopure isoflavans by domino asymmetric transfer hydrogenation/deoxygenation with dynamic kinetic resolution.

Desymmetrization of a p-quinone monoacetal by organocatalytic sulfa-Michael addition provided rapid access to a C-ring building block for a formal synthesis of (-)-codeine. By means of a diastereoselective 1,2-addition for A/C-ring union, an intramolecular nitrone cycloaddition for construction of the phenanthrene core, and a sulfoxide elimination, an enantiopure key intermediate of the authors' previous synthesis of racemic codeine was available in 12 steps from isovanillin.

The first total synthesis of the title diterpene was accomplished starting from the Wieland-Miescher ketone. A diastereoselective sulfa-Michael addition enabled the generation of the delicate β,γ-unsaturated ketone moiety, while the tetracyclic kempane skeleton was readily constructed through domino metathesis.

Die erste Totalsynthese des Titelditerpens wurde ausgehend vom Wieland-Miescher-Keton erreicht. Eine diastereoselektive Sulfa-Michael-Addition ermoglichte die Erzeugung der empfindlichen β,γ-ungesattigten Ketoneinheit, wahrend das tetracyclische Kempan-Gerust problemlos durch Dominometathese aufgebaut wurde.

A ruthenium-catalyzed asymmetric transfer hydrogenation of racemic isoflavanones with dynamic kinetic resolution yields virtually enantiopure isoflavanols as single diastereomers. Subsequent oxidation gives rise to isoflavanones in high enantiomeric purities.

Some novel chromene and pyrano[2,3-c]pyrazole derivatives could be achieved successfully by reacting cyclic β-diketones with 2-acetylfuran/2-acetylthiophene and malononitrile in a one-pot synthesis. Active methylene pyrazolones reacted with 2-(1-furan-2-yl-ethylidene)-malononitrile and 2-(1-thiophen-2-yl-ethylidene)-malononitrile derivatives to afford the desired pyrano[2,3-c]pyrazole derivatives. Structures of all new compounds were established based on analytical and spectral data as well as X-ray crystallography. A plausible mechanism for the reaction is suggested. The solvents and catalyst used are environmentally benign, and no hazardous solvents or heavy metals were involved.

A concise and highly enantioselective synthesis of the natural flavans kazinol U and (2S)-7,3'-dihydroxy-4'-methoxyflavan is reported for the first time. The key transformation is a single-step conversion of a racemic flavanone to a flavan by means of an asymmetric transfer hydrogenation/deoxygenation cascade with kinetic resolution.

Thermal decomposition of an iron-based MOF was conducted under controlled gas environments to understand the resulting porous carbon structure. Different phases and crystallite sizes of iron oxide are produced based on the specific gas species. In particular, air results in iron(III) oxide, and D2O and CO2 results in the mixed valent iron (II,III) oxide. Performing the carbonization under non-oxidative or reducing conditions (N2, He, H2) results in the formation of a mixture of both iron (II,III) oxide and iron (III) oxide. Based on in situ and air free handling experiments, it was observed that this is partially due to the formation of zero-valent iron metal that is rapidly oxidized when exposed to air. Neutron pair distribution function analysis provided insight into the effect of the gas environment on the local structure of the porous carbon, indicating a noticeable change in local order between the D2O and the N2 calcined samples.

Pyrazoles, thiazoles and fused thiazoles have been reported to possess many biological activities. 3-Methyl-5-oxo-4-(2-arylhydrazono)-4,5-dihydro-1H-pyrazole-1-carbothioamides3a,b(obtained from the reaction of ethyl 3-oxo-2-(2-arylhydrazono)butanoates1a,bwith thiosemicarbazide) could be transformed into a variety of thiazolyl-pyrazole derivatives6a–h,10a–c,15a–c,17,19and21via their reaction with a diversity hydrazonoyl chlorides as well as bromoacetyl derivatives. Moreover, the computational studies were carried out for all new compounds. The results indicated that five compounds showed promising binding affinities(10a: − 3.4 kcal/mol,6d: − 3.0 kcal/mol,15a: − 2.2 kcal/mol,3a: − 1.6 kcal/mol, and21: − 1.3 kcal/mol) against the active site of the epidermal growth factor receptor kinase (EGFR). The cytotoxicity of the potent products3a,6d,10a,15a, and21was examined against human liver carcinoma cell line (HepG-2) and revealed activities close to Doxorubicin standard drug. There was an understanding between the benefits of restricting affinities and the data obtained from the practical anticancer screening of the tested compounds.

Grinding a mixture of 6-aminopyrimidine-2,4(1H,3H)-dione 1a or 6-amino-2-thioxo-2,3-dihydropyrimidine-4(1H)-one 1 b or ethyl 7-amino-5-oxo-1-aryl-1,5-dihydro[1,2,4]-triazolo[4,3-a]pyrimidine-3-carboxylate derivatives 5a–c with 1,2-diphenylethanone 2 and aromatic aldehydes 3a–j in the presence of aluminate sulfonic acid nanoparticles (ASA NPs) in a one pot solvent-free conditions, afforded the pyrido[2,3-d]pyrimidinone derivatives 4a–o and ethyl 5-oxo-1-aryl-6,7,8-triphenyl-1,5,6,9-tetrahydropyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine-3-carboxylate derivatives 6a–c, respectively. High yields, short reaction time, easy workup, inexpensive, and reusability of the catalyst are advantages of this method. All structures were elucidated by spectral and elemental analyses. Structures of 6a–c were further proved by alternative synthesis of 6a.

The synthesis of (+)-orientalol F (1) started with aldehyde 6, which is available from (R)-limonene in two steps. Wittig reaction of 6 with unsaturated ylide 7 to give a tetraene, and subsequent ring-closing metathesis yielded hydroazulene 4, selective epoxidation of which gave epoxy ester 3. After generation of the requisite isopropyl unit and regioselective reductive epoxide opening, the derived dienol 2 was used for the installation of the oxygen bridge through intramolecular oxymercuration followed by oxidative demercuration. The resulting allylic alcohol epimers 15 and 16 were readily converted into the target natural product 1 by oxidation/reduction sequences.

Relay metathesis enabled an improved access from (S)-citronellal to the marine trisnorguaiane (-)-clavukerin A. This hydroazulene was applied as an advantageously functionalized building block for the asymmetric synthesis of the sesquiterpene lactone osmitopsin and the proposed structure of 4,5-epoxyosmitopsin using a chemo-, regio-, and diastereoselective diepoxide opening as the key step.

Treatment of 2,4-diphenylbutadiene-1,4-sultone with hydrazine in boiling EtOH gives 1-amino- 2,4-diphenyl-1H-pyrrole. On treatment of 2,4-diphenylbutadiene-1,4 -sultone with phenyl hydrazine in glacial acetic acid, 4,5-dihydro-5-met hyl-1,3,5-triphenyl-1H-pyrazole was isolated. On the other hand, 2,4-diphenylbutadiene-1,4-sulton e reacts with 4 H-1,2,4-triazol-3-amine and 5-amino-3-phenyl-1H-pyrazole to afford the novel heterocyclic compounds 2-(2,2-dioxo-4- phenyl-3,4-dihydro-8H-2λ 6 -(1,2,4)triazolo(5,1- c)(1,2,4)thiadiazin-4-yl)-1-phenylethan-1-one, the structure of which was established by X-ray crystal lography, and 2-(2,2-dioxo-4,7-diphenyl-3,4- dihydro-6H-pyrazolo(5,1-c)(1,2,4)thiadiazin-4-yl)-1-phenylethan-1-one.

A new access to the 6a-hydroxypterocarpan variabilin was established. Key step of this concise total synthesis is a challenging cyclization of a haloketone via halogen–metal exchange and subsequent intramolecular addition to the carbonyl function.

Heterocyclic 2-aminoazo compounds, prepared by ortho-coupling of primary heterocyclic amines with (het)arene diazonium salts, can by transformed by reaction with strong acylating reagents or nitrosyl sulfonic acid into new hetarene-condensed 2-(het)aryl-1,2,4-triazinium and 2-(het)aryl-1,2,3,4-tetrazinium salts, respectively. Their structures could be unambiguously elucidated by means of IR, mass, and NMR spectroscopy as well as, in few special examples, by means of X-ray analysis.