Silver-catalyzed oxidative coupling/cyclization of acrylamides with 1,3-dicarbonyl compounds

An efficient silver-catalyzed oxidative cyclization of acrylamides with 1,3-dicarbonyl compounds is described. It proceeds through a tandem radical addition/cyclization process, in which two new C–C bonds were formed.

Practical identification of eight medically important Trichosporon species by reverse line blot hybridization (RLB) assay and rolling circle amplification (RCA)

We developed a reverse line blot (RLB) hybridization-, and rolling circle amplification (RCA)-based assays for the identification of Trichoporon species and evaluated them with 48 isolates that had been previously recognized as belonging to eight species (Trichosporon asahii, T. cutaneum, T. dermatis, T. domesticum, T. inkin, T. japonicum, T. jirovecii, and T. laibachii). Results were compared to those obtained with DNA sequencing of three rRNA gene loci, i.e., the internal transcribed spacer (ITS) region, D1/D2 domain of the 28S rRNA gene and intergenic spacer 1 (IGS1) region. Using species-specific, or group-specific probes targeted at the ITS region and the D1/D2 domain, the RLB assay permitted accurate species identification of all 48 isolates with 100% specificity. Species-specific RLB probes correctly assigned 45/48 (94%) of the isolates (six species) with the exception of T. dermatis and T. japonicum isolates which were not targeted by the assay. Identification of T. dermatis relied on a positive hybridization result with the group-specific probe hybridizing with T. dermatis and T. jirovecii and the absence of a signal with the T. jirovecii-specific probe. T. japonicum strains were first assigned to the T. asahii-T. japonicum group by hybridization with the two species group-specific probe and then as T. japonicum by the absence of signal with a T. asahii-specific probe. Twelve species-specific RCA probes targeting the eight species studied detected templates of all 48 Trichosporon isolates and an artificial template of T. asteroides, all with good specificity. Both RLB and RCA are potential alternatives to DNA sequencing for the identification of Trichosporon species. The RLB approach is suited for the batched simultaneous analysis of large numbers of isolates, while RCA is more appropriate for the immediate study of single isolates. Comparative costs are US$7 and US$2 per assay for the RLB and RCA methods, respectively.

[Effects of males' age on sperm apoptosis and DNA integrity]

OBJECTIVE

To explore the correlation of males'age with sperm apoptosis, sperm DNA integrity and other seminal parameters.

METHODS

We collected 104 semen samples and divided them into three groups according to the males' age: <35 yr (n = 43), 35 -39 yr (n = 31), and > or = 40 yr (n = 30). Based on the WHO Laboratory Manual (4th ed), we detected the seminal parameters, calculated the percentage of apoptotic sperm by flow cytometry (FCM), determined sperm DNA integrity by Acridine orange staining, and compared the results among the three groups.

RESULTS

There were no statistically significant differences among the < 35 yr, 35 -39 yr and > or = 40 yr groups in semen volume ([2.87 +/- 0.89] ml vs [2.98 +/- 1.09] ml vs [2.65 +/- 0.95] ml), sperm concentration ([60.40 +/- 25.43] x 10(6)/ml vs [69.74 +/- 28.33] x 10(6)/ml vs [55.97 +/- 27.22] x 10(6)/ml) (P>0.05). The percentage of progressively motile sperm was significantly lower in the > or = 40 yr ([39.00 +/- 8.35 %) than in the <35 and 35 -39 yr groups ([48.73 +/- 9.89]% and [45.65 +/- 10.55]%) (P<.0.1), and so was the percentage of morphologically normal sperm in the > or = 40 yr than in the < 35 yr group ([11.11 +/- 8.26]% vs [16.43 +/- 8.75 ]%, P<0.01). The percentage of apoptotic sperm was markedly higher in the > or = 40 yr than in the <35 yr group ([11.82 +/- 5.77]% vs [7.04 +/- 3.50]%, P<0.01), while the sperm DNA integrity significantly reduced in the > or = 40 yr group ([75.52 +/- 10.60]%) as compared with the <35 yr ([86.55 +/- 5.60])% and 35 -39 yr group ( [81.39 +/- 8.94]%) (P<0.01). The males' age was correlated positively with the rate of sperm apoptosis (P<0.01), and negatively with sperm DNA integrity and the percentage of progressively motile sperm (P<0.01).

CONCLUSION

The advance in males' age increases sperm apoptosis and reduces sperm progressive motility, normal morphology and DNA integrity.

[Influence of male age on the outcome of conventional IVF-ET]

OBJECTIVE

To study the influence of male age on the outcome of conventional IVF-ET.

METHODS

Based on male age, 170 couples undergoing conventional IVF-ET were divided into three groups: <35 yr (n = 60), 35 -39 yr (n = 77) and > or = 40 yr (n = 33). We observed the rates of fertilization, cleavage, good quality embryo, implantation, clinical pregnancy and abortion in different groups.

RESULTS

There were no significant differences among the three groups in semen volume ([3.10 +/- 1.22] ml vs [2.84 +/- 1.05] ml vs [2.80 +/- 0.79] ml), sperm concentration ([54.23 +/- 26.07] x 10(6)/ml vs [60.27 +/- 24.80] x 10(6)/ml vs [60.21 +/- 27.42] x 10(6)/ml) and sperm viability ([53.93 +/- 13.25]% vs [56.10 +/- 16.58]% vs [51.82 +/- 15.45]%) (P>0.05). The men of the > or = 40 yr group showed a significantly lower percentage of grade a + b sperm ([40.97 +/- 11.91]%) than those of the <35 and 35 - 39 yr groups ([48.47 +/- 11.78]% and [46.84 +/- 13.51]%) (P<0.05), and morphologically normal sperm ([11.76 +/- 5.97]%) than those of the <35 yr group ([15.25 +/- 6.94]% (P<0.05). The rates of fertilization, cleavage, good quality embryo, implantation, clinical pregnancy were 81.52%, 82.61%, 52.33%, 18.06% and 33.33% in the > or = 40 yr group, with no significant differences from those of the <35 yr group (83.18%, 82.68%, 56.99%, 22.40% and 40.00%) and the 35 - 39 yr group (78.78%, 80.66%, 55.01%, 21.74% and 38.96%) (P>0.05), while the abortion rate was markedly increased in the > or = 40 yr group as compared with the <35 yr group (36.36% vs 8.33%, P>0.05).

CONCLUSION

Increasing male age is related with decreasing percentages of progressively motile sperm and morphologically normal sperm, but not obviously with the rates of fertilization, good quality embryo, implantation, pregnancy and abortion.

Three new compounds from Dictamnus dasycarpus

Phytochemical investigation of the ethyl acetate extracts from root barks of Dictamnus dasycarpus led to the isolation of three new compounds, named as dasycarpusenester A (1), dasycarpusester B (2), dasycarpusacid (3). Their structures were elucidated as (2S)-4-(2,2-dimethyl-5-oxotetrahydrofuran-3-yl)-2-hydroxypent-3-enoic acid methyl ester (1), (2R)-4-(2,2-dimethyl-5-oxotetrahydrofuran-3-yl)-2-hydroxypent-3-anoic acid methyl ester (2), and (2S)-4-(2,2-dimethyl-5-oxotetrahydrofuran-3-yl)-2-hydroxypent-3-anoic acid (3), respectively, on the basis of modern spectroscopic methods and chemical analysis.

Two new compounds from Dictamnus dasycarpus

Two new compounds, one new pyrrolidine alkaloid and one new eudesmane-type sesquiterpene derivative, named, respectively, as dictamnaindiol and dictamnadiol, were isolated from the EtOAc soluble fraction of the ethanolic extract from the root barks of Dictamnus dasycarpus. Their structures were elucidated as (3α,4β)-3-(6-ethoxy-6-(4-hydroxyphenyl)methyl)-4-(4-hydroxyphenyl)-1-methyl-pyrrolidin-2-one (1) and (1R, 4S, 7S, 10R)-1,11-dihydroxyl-4,14-epoxy-5(6)-eudesmene (2) on the basis of their spectral and chemical analysis.

Sulfoxide-alkene hybrids: a new class of chiral ligands for the Hayashi-Miyaura reaction

Sulfoxide-alkene hybrids are introduced as a new class of chiral heterodentate ligands for the Hayashi-Miyaura reaction. The synthesis of these ligands was achieved without the use of protecting groups. A chiral resolution was performed via simple column-chromatographic separation of the diastereomeric ligands. Both diastereomers proved to be excellent ligands in Rh-catalyzed 1,4-addition reactions, furnishing chiral products with high enantioselectivities and, remarkably, opposite stereoconfigurations.

Palladium-catalyzed cyclization of propargylic compounds

Many groups have explored the scope of the palladium-based cyclization of propargylic compounds since Tsuji's first report in 1985. Through the proper positioning of an internal nucleophilic center and the judicious selection of an appropriate external nucleophile, the synthetic chemist can effectively assert control over the course of the reaction and its products. However, initial investigations were very limited: only heterocyclic compounds were originally synthesized. We have found the palladium-catalyzed cyclization of propargylic compounds to be a very efficient method for producing both carbocyclic and heterocyclic compounds. In this Account, we discuss the cyclization reactions of functionalized propargylic compounds with a variety of nucleophiles that we have developed over the past few years. We also review similar reactions reported by other groups. We focus here on the cyclization of functionalized propargylic compounds containing a carbon nucleophilic center that is in close proximity to the propargylic moiety. We conducted a detailed investigation of their cyclizations with carbon nucleophiles, with nitrogen nucleophiles, with oxygen nucleophiles, and without nucleophiles. We have developed several efficient and useful methods for the synthesis of indenes, naphthalenes, polycycles, and spirocyclic compounds. All of these reactions proceed satisfactorily under very mild conditions; high regio- and stereoselectivity have been observed as well. In the course of our studies, we provided the first demonstration of a novel tandem C-H activation/bis-cyclization reaction of propargylic compounds with terminal alkynes. In addition, we used external nucleophiles to investigate the cyclization of functionalized propargylic compounds that bear an unsaturated carbon-carbon or carbon-heteroatom bond. We presented the first report of the use of external nucleophiles to initiate a novel cyclization of functionalized propargylic compounds containing an electrophile. This revelation provided a fresh perspective through the discovery of a new type of domino cyclization of propargylic compounds. Metal-catalyzed cyclization of propargylic compounds can provide indenes, cyclopentanones, cyclic carbonates, benzofurans, and a range of other cyclic molecules. A thorough understanding of the mechanisms involved in this class of reaction affords exceptional synthetic control, as shown here by our development of efficient procedures and reagents for palladium-catalyzed propargylic cyclizations.