Organo-Cation Catalyzed Asymmetric Homo/Heterodialkylation of Bisoxindoles: Construction of Vicinal All-Carbon Quaternary Stereocenters and Total Synthesis of (-)-Chimonanthidine.

A novel chiral spirocyclic amide (SPA)-derived triazolium organocatalyst has been designed and demonstrated to effect asymmetric homo- and heterodialkylations of various bisoxindoles, enabling enantioselective construction of vicinal all-carbon quaternary stereocenters. These reactions feature excellent enantio- and diastereoselectivities (up to 99% ee and >20:1 dr) as well as good to high yields (up to 89% over two steps). As an application of this methodology, the first asymmetric total synthesis of (-)-chimonanthidine has been achieved.

Improved synthesis of 8-oxabicyclo[3.2.1]octanes via tandem C-H oxidation/oxa-[3,3] Cope rearrangement/aldol cyclization.

A tandem C-H oxidation/oxa-[3,3] Cope rearrangement/aldol reaction of allylic silylethers promoted by T+BF4-(tempo oxoammonium tetrafluoroborate)/ZnBr2 has been successfully developed allowing the efficient construction of 8-oxabicyclo[3.2.1]octanes and their analogs with a wide substrate scope.

Catalytic Asymmetric Cascade Using Spiro-Pyrrolidine Organocatalyst: Efficient Construction of Hydrophenanthridine Derivatives.

A newly developed SPD (spiro-pyrrolidine) organocatalyst has been demonstrated to enable an asymmetric aza-Michael/Michael/aldol cyclization cascade, in which two six-membered rings (B/C) and three stereocenters have been constructed in a catalytic one-step process. It is so far the most efficient method for construction of hydrophenanthridine derivatives featuring high enantioselectivity. The trans- or cis-fused B/C-rings can be selectively assembled in a substrate-controlled manner. Moreover, this cascade could magnify to gram scale without loss of enanioselectivity.

[Mutation screening of VHL gene in a Chinese family with nonsyndromic pheochromocytoma].

OBJECTIVE: To detect the VHL gene mutations in a Chinese family with nonsyndromic pheochromocytoma. METHODS: Mutations of VHL gene were detected in a Chinese family with nonsyndromic pheochromocytoma. Five patients and fifteen relatives were involved in this study. Peripheral blood was collected and total genomic DNA was prepared for polymerase chain reaction (PCR). PCR products of all the three exons of VHL gene were purified and a direct gene sequence analysis was performed. RESULTS: All the five patients presented a codon 125 from Histidine (H) to Proline (P) change at nucleotide 587 (A --> C) in exon 2. Seven members of fifteen relatives were carriers with the same VHL gene mutation. Two carriers were detected with bilateral adrenal tumors and right renal cyst respectively by ultrasonic inspection. CONCLUSION: The novel VHL gene mutation detected in this kindred may be the causative gene. Genetic test can detect the carriers in an early period. It is recommended as a routine method of genetic test in nonsyndromic pheochromocytoma patients.