A first and general route to naphthylisoquinoline alkaloids: the total synthesis of O-methyl-tetradehydro-triphyophylline

The first total synthesis of a naphthylisoquinoline alkaloid is described. The required $\text{ortho}$ selective mixed coupling of the alkaloid moieties 2 and 6 is achieved $\text{intra}$-molecularly by the assistance of a reversibly thrown benzylether type auxiliary bridge.     

Highly convergent route to cyclopeptide alkaloids: total synthesis of ziziphine N

[structure: see text]. A highly convergent protocol to cyclopeptide alkaloids, as demonstrated by the first total synthesis of antiplasmodial agent ziziphine N, is developed. The key elements include construction of its aryl ether unit via Mitsunobu reaction, installation of its enamide part via CuI/N,N-dimethylglycine-catalyzed coupling reaction, and ring closure with coupling agents such as FDDP and DPPA.     

A new entry to Amaryllidaceae alkaloids from carbohydrates: total synthesis of (+)-vittatine

The stereoselective and chiral synthesis of the Amaryllidaceae alkaloid, (+)-vittatine 1, is described; the quaternary carbon in 1 was generated by Claisen rearrangement of a cyclohexenol derived from D-glucose by way of a Ferrier's carbocyclisation reaction and a hexahydroindole skeleton was effectively constructed by intramolecular aminomercuration-demercuration, followed by Chugaev reaction.     

A novel total synthesis of elaeocarpus alkaloids

The novel synthesis of elaeocarpus alkaloids has been achieved employing 1,3-dipolar cycloaddition reaction as a key step.     

A new catalytic route to synthesis of silylgermylethynes

Silylgermylethynes known to be potential organometallic reagents and precursors of optoelectronic materials can be efficiently synthesized via a recently reported catalytic method called silylative coupling of alkynes with vinylsilicon compounds. The reaction of triethylethynylgermane with vinyltrisubstituted silanes catalyzed by [RuHCl(CO)(PR₃)_n] (where R = ⁱPr, Cy, Ph; n = 2-3) under optimal conditions selectively yields respective silylgermylethynes. Silylation of ethynylgermane with divinylsilicon derivatives such as siloxanes, silazanes, bis(silyl)benzene and bis(silyl)ethane gives monoethynylgermyl substituted vinyldisilicon products with high yields and selectivity, however, accompanied by traces of dialkynylgermyl derivatives. All catalytic results as well as those of stoichiometric study on the insertion of ethynylgermane into Ru-Si bond have permitted proposing mechanistic schemes of the reaction examined.     

A new synthetic route to tropane alkaloids. Pseudotropine and tropacocaine

Pseudotropine and tropacocaine have been synthesized by a facile route involving the [4 + 2] nitroso cycloaddition followed by internal S_N2 displacement.     

A new general synthesis route to 1,1,1-trihalopolyfluoroalkanes

1,1,1-Trichloro- and tribromo polyfluoroalkanes have been synthesized from perfluoroalkyl iodides and anhydrous aluminum chloride and bromide respectively. The reaction is also applicable to perfluoroalkylether iodides, though varying amounts of by-products are formed depending on the structure of the starting iodide.     

A new route to zinc-blende CdSe nanocrystals: mechanism and synthesis

We report the possible mechanism of forming of CdSe nanocrystals in the high boiling point solvents with long alkane chains and a novel Non-TOP-Based route to zinc-blende CdSe nanocrystals. A new mechanism shows that there exits a redox reaction in the long alkane chain solvents: Se is reduced to H2Se gas; at the same time, the long alkane chains are oxidated to alkene chains; then, the Cd complex reacts with H2Se to form CdSe nanocrystals. Possible chemical reaction equations involved in the process of forming the CdSe nanocrystals have been discussed. The alkene chain and H2Se were detected respectively by a series of experiments to support the new mechanism. Under the guidance of this mechanism, we have developed a much cheaper and greener Non-TOP-Based route for the synthesis of a size series of high-quality zinc-blende (cubic) CdSe nanocrystals. Low-cost, green, and environmentally friendlier reagents are used, without use of expensive solvents such as trioctylphosphine (TOP) or tributylphosphine (TBP). The new route enables us to achieve high-quality CdSe nanocrystals with sharp ultraviolet and visible (UV-vis) absorption peaks, controllable size (2.0-5.0 nm), bright photoluminescence (PL), narrow PL full width of half-maximum (fwhm) (29-48 nm), and high PL quantum yield (up to 60%) without any size sorting.     

A short and concise route to total synthesis of Dendrodolide L

A short and efficient method for the stereoselective synthesis of Dendrodolide L has been developed from inexpensive and commercially available starting material. This convergent synthesis utilizes Jacobsen kinetic resolution, regioselective ring-opening of epoxide and Yamaguchi macrolactonization as key steps.     

A convergent approach to cyclopeptide alkaloids: total synthesis of sanjoinine G1.

A general strategy for the synthesis of cyclopeptide alkaloids containing an endocyclic aryl-alkyl ether bond has been developed featuring a key intramolecular S(N)Ar reaction. The importance of the N-terminal protective group in the realization of such a strategy is documented. From the appropriate amino acid constituents, the natural sanjoinine G1, a 14-membered para cyclophane, has been synthesized in seven steps with 21% overall yield.     

A new synthetic route to the synthesis of nordasycarpidone derivatives

A new synthetic route for the synthesis of the nordasycarpidone derivative 11 which has hexahydro‐1,5‐methanoazocino[4,3‐b]indol skeleton, is described. Construction of the tetracyclic structure was achieved by catalytic reduction and cyclization reaction of the nitrile derivative. Also many new tetrahydrocarbazole derivatives ( 4, 5, 6, 7, 8, 9 ) and a dasycarpidol derivative ( 10 ) were synthesized.     

A new strategy towards the total synthesis of phenanthridone alkaloids: synthesis of (+)-2,7-dideoxypancratistatin as a model study

A new strategy towards the synthesis of phenanthridone alkaloids has been reported through the synthesis of (+)-2,7-dideoxypancratistatin from D-(-)-quinic acid employing PET initiated carbocyclization of an electron rich aromatics by silylenol ether as a key step.     

A concise asymmetric route to Nuphar alkaloids. A formal synthesis of (-)-deoxynupharidine

[reaction: see text] A stereocontrolled route to Nuphar alkaloids is described that employs a formal [3 + 3] cycloaddition strategy to assemble the piperidine nucleus. The addition of Pd-TMM complexes to aziridine 10 was found to be sluggish; however, the addition of a functionalized allyl Grignard reagent followed by a Mitsunobu condensation reaction provided 11 in high yield. The employment of this route in the formal synthesis of (-)-deoxynupharidine 1 is described.     

A simple approach for the synthesis of azocine alkaloids: The total synthesis of megallanesine

A new three step synthetic route to construct azocine ring system using anion chemistry and intramolecular Friedel-Craft reaction of an ester is presented. This method allows synthesis of azocine ring analogues in excellent overall yields. The designed strategy was applied for the synthesis of naturally occurring magallanesine.     

A short synthetic route to the calystegine alkaloids

An efficient strategy is described for the synthesis of enantiopure calystegine alkaloids. The key step employs a zinc-mediated fragmentation of benzyl-protected methyl 6-iodo-glycosides followed by in situ formation of the benzyl imine and Barbier-type allylation with zinc, magnesium, or indium metal. Stereochemistry in the pivotal allylation is controlled by the choice of the metal. The functionalized 1,8-nonadienes, thus formed, are converted into cycloheptenes by ring-closing olefin metathesis. Regioselective hydroboration and oxidation give the corresponding cycloheptanones, which are deprotected to afford the desired calystegines. Hereby, calystegine B(2), B(3), and B(4) are prepared from D-glucose, D-galactose, and D-mannose, respectively. This route constitutes the shortest synthesis of calystegine B(2) and gives rise to the first total syntheses of calystegine B(3) and B(4).     

A facile approach to the synthesis of securinega alkaloids: stereoselective total synthesis of (−)-allonorsecurinine

A concise stereoselective total synthesis of alkaloid (−)-allonorsecurinine is described utilizing classical reactions such as Grignard, Aldol and Horner-Wittig reactions as the key steps.     

Enantioselective total synthesis of tricyclic myrmicarin alkaloids

[reaction: see text] An enantioselective gram-scale synthesis of a key dihydroindolizine intermediate for the preparation of myrmicarin alkaloids is described. Key transformations in this convergent approach include a stereospecific palladium-catalyzed N-vinylation of a pyrrole with a vinyl triflate, a copper-catalyzed enantioselective conjugate reduction of a beta-pyrrolyl enoate, and a regioselective Friedel-Crafts reaction. The synthesis of optically active and isomerically pure samples of (4aR)-myrmicarins 215A, 215B, and 217 in addition to their respective C4a-epimers is presented.     

A new route to the synthesis of ellipticine quinone from isatin

1-(2-Oxo-2-(pyridin-4-yl)ethyl)indoline-2,3-dione can be prepared and converted by treatment with sodium hydroxide into 2-isonicotinoyl-1H-indole-3-carboxylic acid as a key intermediate which can be transformed into ellipticine quinone in a two step sequence.