Enantioselective synthesis of 2-arylpiperidines from chiral lactams. A concise synthesis of (-)-anabasine

Cyclodehydration of achiral or racemic aryl-delta-oxoacids with (R)-phenylglycinol stereoselectively affords chiral non-racemic bicyclic lactams, from which the enantiodivergent synthesis of (R)- and (S)-2-phenylpiperidine, the diastereodivergent synthesis of cis- and trans-3-ethyl-2-phenylpiperidine, and the enantioselective synthesis of the piperidine alkaloid (-)-anabasine is reported.     

Synthesis of Oligodeoxynucleotides by the Phosphite-Triester Method Using Dimer Units and Different Phosphorous-Protecting Groups

A simple synthesis of phosphoamidite dinucleotides with two different phosphorous-protecting groups and their use for the synthesis of 2′-oligodeoxynucleotides on a polymer support is reported.     

An improved general synthesis of 4-aryl-5-pyrimidinecarboxylates

We wish to report an improved, general synthesis of 4-aryl-5-pyrimidinecarboxylates 1. Two different routes have previously been reported for the synthesis of examples of this class of pyrimidine carboxylates. The parent compound, ethyl 4-phenyl-5-pyrimidinecarboxylate was prepared in low yield by the reaction of s-triazine with ethyl benzoyl acetate. In addition, the enol ether β-ketoaldehyde synthon, ethyl 2-benzoyl-3-ethoxy-2-propenoate, was reported to give 1a in modest yield when reacted with guanidine (2).     

Facile Synthesis of (z)-5-Methyl-3-Phenoxymethylene 4,5-Dihydrofuran-2-One

(z)-α-Alkylidene-α-butyrolactone has been reported as a good plant growth regulator^[1] and as an important intermediate to the synthesis of natural product^[2] in literature. There was no report in the literature for the stereoselective synthesis of α-alkylidene lactones in exocyclic double with the (z)-configuration. Herein, we reported a facile synthesis of (z)-5-methyl-3-(phenoxymethylene)-4,5-dihydrofuran-2-one 4 from a readily available starting material 5-phenoxypent-3-yn-2-one 1 via three-step in good yield. The synthetic route is shown as below (scheme 1).     

Synthesis of 2-Acetylindene

In connection with natural products synthesis, we had need of 2-acetylindene (IV). The only reported synthesis of this compound is by Rupe and Müller in 1921.¹ These workers formylated benzylacetone (I) and cyclized the major compound (assumed to be II) with acid to give a solid, mp 122°, reported to be IV.     

Acyl palladium species in synthesis: single-step synthesis of alpha,beta-unsaturated ketones from acid chlorides

Conditions are reported for the facile, one-pot synthesis of alpha,beta-unsaturated ketones via the palladium-catalysed cross-coupling of acyl chlorides with hydrozirconated acetylenes, and its use in the 2-step synthesis of D-5-O-benzyl deoxyxylulose.     

1,2,1′,2′-双蒽醌-3,12-二羧酸二甲酯的合成

我们合成了化合物5,6,7,8,9,这些化合物的合成至今尚未见文献报道。化合物4虽然是已知化合物,但我们研究了便于实验室制备的方法。     

含苯并三唑色酮及1,3,4-噁二唑啉类化合物的合成

研究了一种简便的合成2位含氮杂环色酮类化合物的方法。1H-苯并三唑与ClCH~2COOH反应制得1H-苯并三唑-1-乙酸(1),以此为原料合成了一系列2位含1H-苯并三唑-1-甲基色酮(5)和相关的1,3,4-噁二唑衍生物(8)。     

Synthesis and structural revision of phomopsin B, a novel polyketide carrying a 10-membered cyclic-ether ring

Total synthesis of the proposed structure 2 for phomopsin B was achieved by using an intramolecular olefin metathesis as a key step. The spectral data, however, did not match with those of the natural product reported. Re-examination of the reported NMR data led to the structural revision of phomopsin B to known dothiorelone A 18. The R configuration of dothiorelone A was determined by total synthesis through a cross-metathesis with a chiral olefin 19.     

Facile,efficient and eco-friendly synthesis of 5-sulfenyl tetrazole derivatives of indoles and pyrroles

A concise, two-step eco-friendly approach towards the synthesis of 5-sulfenyl tetrazole derivatives of indoles and pyrroles, is reported. The synthesis comprises the oxone-mediated thiocyanation of the starting heterocycles towards intermediate 3-thiocyanato indoles and 2-thiocyanato pyrroles, and their subsequent treatment with sodium azide in 2-propanol/water under zinc bromide promotion.     

Synthesis and fluorescent properties of a new photostable thiol reagent “BACM”

The 3-maleimidocoumarin BACM ( 2d ) is a new tag designed to react with thiols in biological materials to form fluorescent derivatives whose emission is in the 500 nm (green) region with good resistance to fading. The fluorescence properties of its N-acetyl-L-cysteine derivative are described. BACM itself is non-fluorescent, as is its predecessor, DACM ( 1a ). A synthesis of BACM is reported which avoids the formation of nitrocoumarin isomers obtained in the reported synthesis of DACM. The synthesis of the related 3-(4-maleimidophenyl)coumarin is also described.     

Enantio- and stereospecific syntheses of 15(R)-Me-PGD2, a potent and selective DP2-receptor agonist

The first total synthesis of 15(R)-Me-PGD2 3 is reported. The synthesis is based on the enantioselective and stereospecific syntheses of synthon 17 and its attachment to the five-membered ring by a olefin cross metathesis reaction. This approach permits the introduction of a side chain with a predetermined stereogenic center into the prostanoid ring, resulting in the synthesis of 15R-methyl prostaglandin D2 and allows rapid access to other prostanoids.     

A linchpin carbacyclization approach for the synthesis of carbanucleosides

A convenient synthesis of carbanucleosides, with both enantiomers equally accessible, is reported. The key step is a tandem linchpin cyclization process to give access to substituted carbafuranose derivatives having the correct relative stereochemistry for subsequent nucleobase introduction with inversion of configuration at C1. This was illustrated by the synthesis of 2',3'-dideoxycarbathymidine via a convergent nucleobase introduction and of 2',3'-dideoxy-6'-hydroxycarbauridine via a linear nucleobase introduction. Both methods relied on Mitsunobu chemistry, and the first example of the Mukaiyama modification of the Mitsunobu reaction involving nucleobases as nucleophiles is reported.     

Synthesis of the common propellane core structure of the hasubanan alkaloids

The racemic synthesis of the common propellane core structure found in various hasubanan alkaloids is reported. The successful completion hinged upon the stereocontrolled construction of the cis-substituted heterobicycle as a precursor for the intramolecular Dieckmann condensation. A novel strategy is introduced for the facile hydrolysis of a sterically demanding carboxamide under a mild condition. The 2-nitroanilide obtained by the Goldberg arylation of a carboxamide with 2-iodonitrobenzene was readily converted to the corresponding ester derivative by way of N-acylbenzotriazole. We expect that the reported synthetic route will allow the synthesis of a series of hasubanan alkaloids starting from the correspondingly functionalized 2-tetralone derivatives.     

A facile and highly stereoselective synthesis of (2E)-, (2E,4E)-unsaturated amides and related natural products

A facile synthesis of (2E)-, (2E, 4E)-unsaturated amides was achieved via arsonium bromides with high stereoselectivity. Its application to the synthesis of related natural products 4 and 5 is also reported.     

First synthesis of caerulomycin B. A new synthesis of caerulomycin C

Caerulomycins produced by Streptomyces caeruleus are bipyridinic molecules endowed with antibiotic properties. The first synthesis of caerulomycin B (1) as well as a new synthesis of caerulomycin C (2) are reported. Starting from 3-hydroxypyridine, the same methodology was used to prepare both compounds 1 and 2. Efficiently controlled reactions such as metalation to allow the synthesis of 2,6-diiodo-3,4-dialkoxypyridines, which are key intermediates, and further halogen-lithium exchange and cross-coupling to reach the targets molecules 1 and 2 have been developed.     

Total synthesis of d,1-occidentalol by photoannelation

A nine step synthesis of an intermediate previously used in the synthesis of the sesquiterpene occidentalol is reported which incorporates a 2+2 photocycloaddition reaction as the key carbon carbon bond forming step.     

Chemistry of the phenoxathiins. III. Synthesis of benzo[1″,2″:5,6:5″,4″:5′,6′]bis[1,4]oxathiino[3,2-b:3′,2′-b']dipyridine

As a result of studies dealing with the synthesis of 1-azaphenoxathiins, the synthesis of benzo[1″,2″:5,6:5″,4″:5′,6′]bis[1,4]oxathiino[3,2-b:3′,2′-b']dipyridine was examined. Unique evidence of solvent participation in the synthesis of these compounds by the structure elucidation of a novel minor by-product formed during the synthesis of the title compound is also reported.     

用于CO2或CO加氢合成甲醇过程的高活性Cu/ZnO/Al2O3纳米纤维催化剂

 采用特殊的共沉淀法制备了一种在CO2加氢和CO加氢过程中都具有很高活性的Cu/ZnO/Al2O3纳米纤维催化剂. 与商业催化剂相比,该催化剂的CO2和CO转化率、甲醇选择性和甲醇时空产率高很多. 该合成方法不需要有机试剂和复杂的过程,因此生产成本低,容易实现.     

Solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition

The solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition of polymer-bound azides to various alkynes is reported. Polymer-bound azides were synthesized from polymer-bound halides and sodium azide and reacted with alkynes to produce polymer-bound 1,2,3-triazoles. Cleavage of the triazoles was performed with trifluoroacetic acid. A traceless synthesis of 1,2,3-triazoles was developed using 2-methoxy-substituted resin (polymer-bound 4-hydroxy-2-methoxybenzyl alcohol). In addition, a synthesis of 4-hydroxybenzyl-substituted 1,2,3-triazoles from the bromo-Wang resin (4-(bromomethyl)phenoxymethyl polystyrene) was achieved.