Enantioselective hydrogenation of alpha-aryloxy and alpha-alkoxy alpha,beta-unsaturated carboxylic acids catalyzed by chiral spiro iridium/phosphino-oxazoline complexes.

The iridium-catalyzed highly enantioselective hydrogenation of alpha-aryloxy and alpha-alkoxy-substituted alpha,beta-unsaturated carboxylic acids was developed. By using chiral spiro phosphino-oxazoline ligands, the hydrogenation proceeded smoothly to produce various alpha-aryloxy- and alpha-alkoxy-substituted carboxylic acids with extremely high enantioselectivities (ee up to 99.8%) and reactivities (TON up to 10,000) under mild conditions. The hydrogenation of alpha-benzyloxy-substituted alpha,beta-unsaturated acids provided an efficient alternative for the synthesis of chiral alpha-hydroxy acids after an easy deprotection. A mechanism involving a catalytic cycle between Ir(I) and Ir(III) was proposed on the basis of the coordination model of the unsaturated acids with the iridium metal center. The rationality of the catalytic cycle, with an olefin dihydride complex as the key intermediate, was supported by the deuterium-labeling studies. The X-ray diffraction analysis of the single crystal of catalyst revealed that the rigid and sterically hindered chiral environment created by the spiro phosphino-oxazoline ligands is the essential factor that permits the catalyst to obtain excellent chiral discrimination. A chiral induction model was suggested on the basis of the catalyst structure and the product configuration.

Iridium-catalyzed enantioselective hydrogenation of alpha,beta-unsaturated carboxylic acids.

A highly efficient iridium-catalyzed hydrogenation of alpha,beta-unsaturated carboxylic acids has been developed by using chiral spiro-phosphino-oxazoline ligands, affording alpha-substituted chiral carboxylic acids in exceptionally high enantioselectivities and reactivities.

[Study on the timeliness of the notifiable communicable diseases surveillance system in Fujian province, China, 2004].

OBJECTIVE: To understand the timeliness of the notifiable communicable diseases surveillance system in Fujian province. METHODS: Database from the internet based communicable diseases reporting system was used. RESULTS: The 50th percentile of time between the disease diagnosed and report recorded in medical faculties was 1 day in 2004 which was 6 days less than that in 2001 - 2003. The timeliness rate of 0 day was 46.46%, a 2.7 times over that in 2001 - 2003. The timeliness of notifiable communicable diseases surveillance system in different administrative areas, reporting units and on different diseases was significantly different. Time between the disease diagnosed and report recorded was the shortest in those cases reported by hospitals and traditional Chinese medicine(TCM) hospitals at the county level and above, with 50th percentile as 0 day, but the timeliness rate of 0 day was 50.76% with 70.04% of the cases were reported from hospitals and TCM hospitals of county level and above. Length between the disease diagnosed and reported was the longest in those cases recorded by Centers for Disease Control and Prevention(CDCs) with the 50th percentile as 3 days. The source of cases recorded by CDCs came from hospitals at the township level, where there was no connection to internet but the reporting cards had to be sent to local CDCs. Time between the disease being diagnosed and reported was 2 days in those cases reported by hospitals at the township level. 21.21% of cases were recorded by hospitals of township level and CDCs. The 50th percentile of time shown between the reported records and confirmed by CDCs was 4 hours The 24 hour timeliness rate was 63.65%. CONCLUSION: The timeliness of the notifiable communicable diseases surveillance system had been improved significantly after the medical personnel recording the cases directly through internet. Timeliness could be further improved through access to internet at the hospitals of township level, training of staff and better hospital management systems.