Efficient and Facile Synthesis of ( ± )-Salvirecognine

Salvirecognine (7) is a diterpene isolated from Salvia recognita[1] which has been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family. [2] In order to study further relationships between the structure and biological activity of the diterpene compounds and as an extension of diterpenoid synthesis in our laboratory, [3,4] the first total synthesis of the title compound was achieved by an efficient and facile route (Scheme 1).     

Study on the Ring Eulargment Reaction: Synthesis of 7,8,13, 13a-tetrahydroisoindolo[1,2-b][3]benzazepine and 5,6,8,9,14,14a-hexahydroisoquino[1,2-b][3]benzazepine

In our research on the ring enlargement of certain N-heterocycles, a general procedure for the ring enlargement with the insertion of an extra -CH2- was improved and shown in Scheme I1.Scheme IThe procedure had been carried out with such N-heterocycles as 2-methyl-1,2,3,4-tetrahydroisoquinoline2, tetrahydroberberine and strychnine3 with expected results. Thus, the procedure shown in Scheme I provides a new approach to the synthesis of larger N-heterocycles.Isoindolo[1,2-b][3]benzazepines a…     

Synthesis of a Polymer-bound Sensitizer and its Application in the Photoisomerization of trans-Vitamin D_3 to cis-Vitamin D_3

The photochemistry of the vitamin D family and their precursors has been the subject of extensive studies for many years1-4. Most of the studies focus on the photoisomer- ization of 7-dehydrocholesterol and that of tachysterol to previtamin D3, which is of commercial importance in the synthesis of vitamin D34, 5. Recently the cis/trans isomerization of vitamin D analogs (Scheme 1) draws attention because of its importance in the synthesis of hydroxylated vitamin D metabolites6. However, o…     

Erythrocentaurin, Biosynthesis Postulation and Biomimetic Synthesis

Erythrocentaurin is a relatively simple nature product isolated from the root of Gentiana macrophylla Pall.[1] The co-existed of gentiopicroside from the same species led to speculation that erythrocentaurin is a biosynthesis product of gentiopicroside. The transformation of secologanin to carbocyclic aglycone under biomimetic condition has already known (Scheme 1).[2,3] The postulated biosynthesis pathway of erythrocentaurin may be in the same way. In the process the cyclic hemiacetal of the aglycone opened to the dialdehyde which then undergoes a vinylogous aldol reaction, and then dehydroxylation and double bond migration to the title compound (Scheme 2).     

Study on the interactions between anti-tumor metal complexes and mononucleotides using trans-[en_2Os(η~2-H_2)(CF_3SO_3)](CF_3SO_3) as a ~1H NMR probe in a competitive mode

Trans-[en_2Os(η~2-H_2)]2 , the structure of which is shown in Scheme l, as described in an earlier paper[l] shows promise of being a useful and versatile probe for research on biomolecules. It has been shown to bind to a variety of biomolecules such as n…     

A Novel Approach to Synthesis of Tricyclic Diterpenoid

A novel approach has been found and the first total synthesis of (±)-Salvirecognine was accomplished by using it. In which intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously to afford key intermediates for synthesis of aromatic tricyclic diterpenoids OMe PPA O O O OMe 1 2 Scheme 1 As shown in Scheme 1 intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously when compound 1 was treated by PPA at 125 ℃. In which the i-pr…     

Synthesis of cis-(±)-2-Hydroxymethyl-5-(Cytosine-1'-yl)-1,3-Oxathiolane (BCH-189)

cis-BCH-189 are potent anti-HIV agents and have been synthesized from mannose1 galactose2 or glucose3 etc. Owing to so many synthetic steps, it is difficult and expensive to obtain a few grams. In this paper, we have designed new route and promoted the reaction conditions for the synthesis of this nucleoside cis- (+)- BCH-189 from cheap starting material via a four step route as shown in Scheme 1. By this method, a series of derivatives of title compound can be synthesized conviniently for…     

Toward Total Synthesis of Yohimbine and Reserpine Alkaloids;Part 1.An Improved Synthesis of cis-5,8-Dihydroxy-1,4,5,8,9,10-hexahydronaphthalene-1,8-lactone via Selective Reduction of the Conjugated Ketone with Zn(BH_4)_2

cis-5, 8-Dihydroxy-1, 4, 5, 8, 9, 10-hexahydronaphthalene-1, 8-lactone 7 is the key intermediate to build E ring 2 possessing five chiral centers in total synthesis of (-)-reserpine 11, 2. In 1958, Woodward firstly reported an artful route to the synthesis of (-)-reserpine from the acid 4. One major drawback of this promising approach is the low yield obtained in the synthesis of the required lactone 7. Herein, we described an efficient and improved method for the synthesis of 7 as shown …     

Facile Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones Catalyzed by Ceric Ammonium Nitrate (CAN) under Ultrasound Irradiation

Indole fragment is featured widely in a wide variety of pharmacologically and biologically active compounds.[1] The 3,3-bis(3-indolyl)oxindole has been shown to possess antibiotic activities against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. [2] As a continue of our work on the synthesis of indole derivates such as bis(indolyl)methanes,[3]we describe an ultrasound-accelerated reaction of isatin 1 with indoles 2 using a catalytic amount of ceric ammonium nitrate (CAN), which provides an efficient route to the synthesis of 3,3-di(1H-indol-3-yl)indolin-2-ones.     

Synthesis of 1,7-Bis(4-hydroxyphenyl)hepta-4E,6E-dien-3-one

Diarylheptanoids, most of which appearing in the areas of anti-inflammatory, anti-oxidative, super-oxide scavenging and anti-hepatotoxic effects, constitute a distinct group of metabolites of natural plants characterized by two aromatic rings linked by a linear seven aliphatic chain. We have investigated this kind of compounds and made some progress.[1]1,7-Bis(4-hydroxy-phenyl)hepta-4E,6E-dien-3-one (1) was firstly isolated from the seeds of Alpinia blepharocalyx.[2] So far the synthesis of the compound has not been reported yet. Herein, we report the synthesis of compound 1. The synthetic route is outlined in Scheme 1.     

PhI(OAc)_2-promoted umpolung acetoxylation of enamides for the synthesis of α-acetoxy ketones

Umpolung is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficient PhI(OAc)_2-promoted umpolung acetoxylation reactions of enamides was developed for the synthesis of α-acetoxy ketones. The reaction tolerates a wide range of functional groups and affords α-acetoxy ketones in good to excellent yields. PhI(OAc)_2 serves as a source of acetoxy in the reaction.     

Effect of Polymerization Temperature on Propylene Polymerization with Cs-symmetric Metallocene Catalyst

The synthesis of bridged ansa metallocenes usually gives a diastereomeric mixture ofracemic and meso metallocene isomers and in many cases the meso form is about 50 % ofthe product of metallocene synthesis"'. The amount of desired racemic isomer is ratherpoor and can be separated from the meso isomer by fractional crystallization'. The racemicansa-metallocene isomer acts as catalyst for propylene polylnerization to produce isotacticpolypropylene (PP) while the corresponding meso isomer gives a…     

First Synthesis of 3''''- Geranyl-2'''', 3,4,4''''-tetrahydroxychalcone with 5 α- Reductase Inhibitory Properties

The geranylated chalcone 1,3′-geranyl-2′, 3,4,4′-tetvahydroxychalcone with high 5α-reductase inhibitory prop erties, was isolated from Artocarpus incisus by Shimizu in 2000. [1] Herein, we describe the first synthesis of the natural product 1 by four steps starting from compounds 2 and 7. The synthetic route was shown in Scheme 1:     

Synthesis and Crystal Structure of Ferrocenesulfonyl Benzimidazole Derivatives

Ferrocene derivatives have attracted much attention over the past two decades in many fields due to their diversebiological activities. [1,2] As a part of a continuing investigation into these compounds, we report here six novel com pounds and the crystal structure of 2a. The synthetic routes of the novel compounds are shown in Scheme 1.     

Adsorption desulfurization of model gasoline by metal–organic framework Ni_3(BTC)_2

This work presented the synthesis of Ni-based metal-organic framework material with a paddle-wheel structure Ni_3(BTC)_2(Ni-BTC) and its application in thiophene(TP) adsorption from gasoline distillate by batch method. Adsorption isotherms of TP, cyclohexene, and toluene in cyclohexane onto Ni-BTC were conducted at 298–308 K to interpret the different effect of cyclohexene and toluene on TP adsorption.The results showed that, compared with cyclohexene, toluene addition in model gasoline led to a more evident decline in sulfur capacity of Ni-BTC, which is opposite to isostructural HKUST-1. The adsorption isotherms of TP, cyclohexene and toluene fit Langmuir model, S-type model and Temkin model well, respectively, indicating that the adsorption mechanisms of TP and the two competitors are different from one another. The adsorption capacities on Ni-BTC followed the order of cyclohexene toluene TP at the same equilibrium concentrations, implying the order of the adsorption affinities, which is in good agreement with the different extent of influence by the two competitors. The enthalpy of TP adsorption on Ni-BTC was estimated to be-80.01 kJ/mol, almost twice that on HKUST-1. The poor reusability of Ni-BTC in batch experiment, which is owing to its sensitivity to the air, can be prevented from regenerating used Ni-BTC in fixed-bed reactor by N_2 flow. The difference between Ni-BTC and HKUST-1 in maximum adsorption capacity(q_0), H of TP adsorption, and stability demonstrates that the central metal in isostructural MOFs plays a key role in adjusting the desulfurization performance, which may open up a potential avenue for the development of MOF-based adsorbents with superior desulfurization performance.     

(Et_4N)_2[Fe_4(SPh)_10] Stimulated S_(RN)1 Reactions of α-Bromonaphth-alene with Pinacolone Carbanion

The studies of the radical chain nucleophilic substitution reaction (SRN1) have been active field in both mechanism and organic synthesis research1-4. The mechanism is a well known process by which a nucleophilic substitution is produced on a non-actived adequated substituted substrate. It is a chain process which involves radicals and radical anions as intermediates. The main steps of this mechanism are sketched in scheme 1. As stimulated methods of initiation step, the photostimulated5-7, …     

A Novel Exact Fixed-node Quantum Monte Carlo Algorithm

In this paper we proposed a novel exact fixed-node quantum Monte Carlo (EFNQMC)algorithm,which is a self-optimizing and self-improving procedure,In contrast to the previous EFNQMC method,the trial function is optimized synchronistically in the diffusion procedure,but not before the beginning of EFNQMC computation.In order to optimize the trial function,the improved steepest descent technique is used,in which the step size is automatically adjustable.The procedure is quasi-Newton and converges super linearly.We also use a novel trial function,which has correct electron-electron and electron-nucleus cusp conditions.The novel EFNQMC algorithm and the novel trial function are employed to calculate the energies of 1^1A1 state of CH2,^1Ag state of C8 and the ground-states of H2,LiH,Li2,H2O,respectively.The test results show that both the novel algorithm and the trial function proposed in the present paper are very excellent.     

Fuzzy model prediction of Co (III)Al2O3 catalytic behavior in Fischer-Tropsch synthesis

The application of Co(Ⅲ)/Al2O3 catalyst in Fischer-Tropsch synthesis(FTS)was studied in a wide range of synthesis gas conversions and compared with Fuzzy Simulation results.Present study applies fuzzy model to predicting the product composition of CH4,CO2 and CO in Fischer-Tropsch process for natural gas synthesis,in which the input vector was 4-dimension including four variables(operating pressure, operating temperature,time and CO/H2 ratio)of 70 different experiments and the output product is a composition of CO2,CO and CH4. The Mamdani algorithm has been applied to the training of the fuzzy system and the test set was used to evaluate the performance of the system including R2,ARE,AARE and SD.The results demonstrated that the predicted values from the model were in good consistency with the experimental data.The work indicates how fuzzy inference system(FIS),as a promising predicting technique,would be effectively used in FTS.     

Stereoselective Synthesis of 2,3,4,6-Tetrasubstituted Tetrahydropyrans

The construction of stereodefined, highly substituted tetrahydropyrans has attracted a lot of interest over the years since they constitute ubiquitous fragments of numerous biologically active natural products.[1] During the course of our synthetic studies toward ambruticin, a fascinating antibiotic[2] which came back in the front scene with three recent total synthesis, [3] we have been interested in the synthesis of 2,3,4,6-tetrasubstituted tetrahydropyrans 5 (Scheme 1). [4] Moreover, this kind of subunit is found to be embedded in several other natural products such as lasonolide A, polycavernoside A, ratjadone, or concanamycin A.     

OBSERVATION OF A COMPETITIVE PATH IN THE NUCLEOPHILIC ADDITION REACTION OF FLUOROOLEFINS:THE BROMOPHILIC REACTION OF THE ADDUCT CARBANION INTERMEDIATE

The nucleophilic addition reaction of per-or polyfluoroolefins with nucleophileshas been studied extensively and is generally considered to involve steps such as(1),(2)and(3)shown in Scheme 1.But in the reactions of bromotrifluoroethene(3)with alkoxides RO~-(2),besides the normally expected products ROCF_2CFBrH(4)