Divergent Asymmetric Total Synthesis of Mulinane Diterpenoids.

A concise, divergent, asymmetric total syntheses of mulinane diterpenoids has been achieved. Specifically, a new strategy was developed featuring a key intramolecular Friedel-Crafts reaction to construct the chiral fused 5-6-6 tricyclic motif, followed by sequential Birch reduction, conjugate methylation, and homologation/ring-expansion reactions to furnish the desired 5-6-7 tricyclic skeleton bearing five contiguous stereocenters. With this efficient strategy, seven mulinane diterpenoids and two analogues were synthesized via late-stage functional modification or functionalization in 8.6-20 % overall yields and 11-15 steps.

Total Synthesis of the Alleged Structure of (+)-Fimbricalyxoid A.

An enantioselective total synthesis of the alleged structure of (+)-fimbricalyxoid A is reported. The synthetic strategy features a pyridine-N-oxidate-mediated SN2' reaction to introduce an oxygen functionality at position C3 of the A-ring and a sequential three-step process via the cleavage of the C-O bonds and hemiketalization to form the 3,20-oxybridge. With this strategy, the target molecule was synthesized in 19% overall yield and 12 steps from our previously synthesized cis-fused octahydrophenanthrene (+)-6.

A Three-Step Process to Facilitate the Enantioselective Assembly of Cis-Fused Octahydrophenanthrenes with a Quaternary Stereocenter.

A three-step process for the enantioselective assembly of cis-fused octahydrophenanthrenes with a quaternary stereocenter is reported. This synthetic strategy relies on a regioselective γ-alkylation, a one-pot sequence of asymmetric hydrogenation and oxidation, and an intramolecular enolate arylation to facilitate the rapid and enantioselective construction of cis-fused octahydrophenanthrene scaffolds with an arylated all-carbon quaternary stereocenter concisely and efficiently.

Asymmetric Hydrogenation of ß-Aryl Alkylidene Malonate Esters: Installing an Ester Group Significantly Increases the Efficiency.

Herein, we report a practical method for efficient asymmetric hydrogenation of ß-aryl alkylidene malonates. With a site-specifically tailored chiral spiro iridium catalyst, a series of ß-aryl alkylidene malonate esters were hydrogenated to afford chiral malonate esters with good to excellent enantioselectivities (up to 99% ee) and high turnover numbers (up to 19000). The results showed that installing an ester group in α,ß-unsaturated carboxylic esters significantly increased the efficiency of their asymmetric hydrogenation reactions.

Asymmetric Hydrogenation of Tetrasubstituted Cyclic Enones to Chiral Cycloalkanols with Three Contiguous Stereocenters.

A highly efficient iridium-catalyzed asymmetric hydrogenation of tetrasubstituted cyclic enones has been developed for the enantioselective synthesis of chiral cycloalkanols with three contiguous stereocenters. The C═O and C═C bonds of the enone substrates were hydrogenated sequentially in one pot with excellent enantioselectivity (92 to >99% ee) and diastereoselectivity (dr 95:5 to >99:1). The reaction provided a practical approach to all of the stereoisomers of the antiulcer drug rosaprostol.

[Analysis of articles and citations of Chinese Journal of Pediatrics from 1950 to 2009].

OBJECTIVE: To explore the articles, authors and citations of the articles published in Chinese Journal of Pediatrics, and have a clear view of the characteristics of this journal in its different development stages. METHOD: Bibliometric methods were used to analyze the published articles, cooperation, regional distribution, core authors, corresponding authors and high-quantities of publication institutes, and also to calculate the number of citations per paper, types of citations, language-based citation number, Price index, self-cited rate and the distribution of journals based on citations. RESULT: Totally 5534 academic articles were published during the 60 years, of which the number of articles written by more than one author was 4669 (80.71%), with a degree of collaboration as 3.87, and a rate of collaboration as 84.37%. The number of articles by a single author was 865 (19.29%). As for the regions from where the papers were submitted, the top one was Beijing, which had 1495 articles published (27.01%). The top 15 institutes in number of articles had published 2254 articles (40.73%). The average citation rate was 84.15%, and the number of citations was 48 854. The number of citations per paper was 10.06, the Price index and self-cited rate were 55.57% and 6.12%, respectively. The number of citations from foreign language literature was 35 781 (69.1%). The citation number of journals was 43 266 (84.5%), which is markedly higher than the citations of books and others. CONCLUSION: Chinese Journal of Pediatrics has a wide distribution of authors and a high cooperative rate. This journal has a group of high-level core authors since founded in 1950, and it shows an adequate ability of absorbing and using scientific information. The articles published in this journal not only objectively reflected the distribution of the research powers, but also the development status of pediatrics in our country.

[An analysis of articles published in Chinese Journal of Pediatrics from 1996 to 2005].

OBJECTIVE: To explore, on the basis of principles of bibliometrics, the distribution of the authors of the articles published in Chinese Journal of Pediatrics, and the types of the institutions and the different regions from where the manuscripts were submitted in order to make a clear view of the characteristics and the status of cooperations in pediatric research work; to ascertain, among them, the core authors, core institutes and core regions; and to analyze the significance of corresponding authors, a new regulation adopted by this Journal in recent years, and to explore, furthermore, the funding status of the studies. METHOD: Based on the information drawn from Chinese Medical Current Content (CMCC), bibliometric method was used to analyze the publications in Chinese Journal of Pediatrics and their authorship during the period from 1996 to 2005. RESULT: Totally 3337 academic articles were published during the ten years; of which the number of articles written by more than one authors was 2951, accounting for 88.43 %, with a degree of collaboration as 4.12. The number of articles by a single author was 386 (11.57%). A total of 234 core authors contributed to 1031 research papers published (30.90% of all). As for the regions from where the papers were submitted, the top one was Beijing, which had 968 articles published (29% of all). And for the institutes, the number of the papers from the hospitals affiliated to medical schools was 2095 (62.78% of all), ranked the first. The second was research institutes which had 261 articles published in the Journal (7.82%), and 68 articles were from colleges and universities which ranked the third (2.03%). The top 10 institutes in number of papers had published 1273 articles (38.15% of all). The articles, from research projects funded by certain grants published in this Journal increased almost every year, from 7.44% of 1996 to 25.82% of 2005', which reflected timely and objectively a growing tendency in pediatric research and that funded research projects by certain garnts could be an important support to the publication of academic papers. The corresponding authorship as a signature regulation was introduced by this Journal in 1999, which played a positive role in pushing the leading work of key authors in construction of research groups. There were 2243 articles of pediatric clinical studies, (67.22%) and 1094 of basic research (32.78%). CONCLUSION: Chinese Journal of Pediatrics had a wide distribution of authors and a high cooperative rate. This Journal had a group of core authors who were strong in academy, active in research and productive in papers, and had a strong positive impact on this Journal. But it was also revealed that the research powers in the field of pediatric study were not evenly distributed. The guideline adopted by and for this Journal was clear and correct. The articles published in this Journal not only objectively reflected the distribution of the research powers and the latest achievements in pediatric study over the country, but also had its focus, which played a certain leading role in pediatric research.