Biao Jiang

Selective Aerobic Oxidation of Alcohols to Aldehydes, Carboxylic Acids, and Imines Catalyzed by a Ag-NHC Complex

Silver NHC catalysts have been developed for the selective oxidation of alcohols to aldehydes or carboxylic acids in the presence of BnMe3NOH or KOH under dry air. The aerobic oxidation conditions are mild, and the yield is excellent. Further tandem catalysis enables the one-pot synthesis of imines in excellent yield. Only 0.1 mol % of the catalyst is required.

Lewis acid promoted alkynylation of imines with terminal alkynes: simple, mild and efficient preparation of propargylic amines

Abstract A mild and efficient addition of terminal alkynes to imines in the presence of ZnCl 2 , Et 3 N and TMSCl gives propargylamines in good yields.

Alkynylation of carbonyl compounds with terminal acetylenes promoted by ZnCl2 and Et3N: simple, mild and efficient preparation of propargylic alcohols

Abstract A mild and efficient addition of terminal acetylenes to carbonyl compounds in the presence of ZnCl 2 and Et 3 N gives propargylic alcohols in good to high yields.

Enantioselective alkynylation of a prochiral ketone catalyzed by C2-symmetric diamino diols

Abstract C 2 -Symmetric diamino diols were used as chiral ligands to induce the asymmetric addition of lithium acetylides to carbonyl groups. The enantiomeric excesses (up to 99% ee) depended on the structure of the acetylene.

Progress in studies of novel marine bis(indole) alkaloids

The marine sponges are the source of a unique group of natural products featuring a novel skeleton, the two indole rings were directed linked by a central heterocyclic moiety. Since topsentin, a bis(indolyl)imidazole, and its analogues were isolated from Topsentia genitrix about a decade ago, scientists have isolated various novel bis(indole) alkaloids from marine organisms especially from deep-water sponges in succession. Over the last 15 years there has been an ever-increasing interest in the biological activity of these molecules. These studies became possible as a result of the scientific development of isolation, purification and total synthesis methods concomitant with the development of fairly simple in vitro tests. This paper offers a general view of the recent progress in the field of novel marine bis(indole) alkaloids, including the topsentins, nortopsentins, rhopaladins, hamacanthins, and dragmacidins family natural products. It focuses on the isolation, structure determination, and total synthesis of these bioactive alkaloids.

Asymmetric aminohydroxylation of vinyl indoles: a short enantioselective synthesis of the bisindole alkaloids dihydrohamacanthin A and dragmacidin A

Abstract A useful approach for the direct enantioselective synthesis of (S)-N-Boc-protected α-indol-3-ylglycinols from vinyl indoles using the Sharpless asymmetric aminohydroxylation reaction, with enantioselectivities of up to 94% and isolated yields of up to 65%, is described. Expeditious enantioselective syntheses of hamacanthin A and dragmacidin A have been achieved using the corresponding N-Boc-protected α-6-bromo-indol-3-ylglycinol as the key intermediate. Furthermore, the absolute stereochemistry of cis- and trans-dihydrohamacanthin A has been determined through the enantioselective total synthesis of the unnatural enantiomers.

A highly stereoselective synthesis of indolyl N-substituted glycines

Abstract Optically active α-indolyl N-substituted glycines were synthesized by reaction of an indolyl boronic acid with glyoxylic acid using chiral methylbenzylamine as the chiral auxiliary with high diastereoselectivity. The absolute configuration of the product was determined by a single-crystal X-ray analysis.

Highly enantioselective reduction of achiral ketones with NaBH4/Me3SiCl catalyzed by (S)-α,α-diphenylpyrrolidinemethanol

Abstract The reducing agent prepared from sodium borohydride, trimethylsilyl chloride and a catalytic amount of ( S )-α,α-diphenylpyrrolidinemethanol has been successfully applied to the enantioselective reduction of ketones. The optically active secondary alcohols were obtained in excellent enantiomeric excess and almost quantitative chemical yield.

Functional Role of Asparaginyl Endopeptidase Ubiquitination by TRAF6 in Tumor Invasion and Metastasis

BACKGROUND Asparaginyl endopeptidase (AEP) has been implicated in human cancer development. However, the molecular mechanisms underlying AEP regulation, including the role of pro-AEP activation, remain elusive. METHODS We investigated the regulation of AEP by TRAF6 and its effects on tumor progression and metastasis in cancer cell lines, murine models, and specimens from patients using biochemical analyses, confocal microscopy, immunoelectron microscopy, and migration-invasion assays. The sera of healthy donors and breast cancer patients were examined by enzyme-linked immunosorbent assay, and a tissue array of 314 breast cancer specimens was assessed for AEP and TRAF6 by immunohistochemistry. Furthermore, the effects of AEP inhibitors or monoclonal antibodies on pulmonary metastasis were evaluated in murine models. The statistical significance between groups was determined using two-tailed Student t tests. RESULTS We demonstrate that TRAF6 ubiquitinates the proform of AEP through K63-linked polyubiquitin, reversible by USP17, and forms a complex with HSP90α to subsequently promote pro-AEP intracellular stability as well as secretion. Disrupting the interaction between pro-AEP and TRAF6 or inhibiting HSP90α reduced pro-AEP secretion and consequently reduced tumor metastasis. Higher circulating AEP levels were detected in the sera of breast cancer patients, and AEP inhibitors or neutralizing antibodies remarkably decreased tumor metastasis in murine models. Notably, TRAF6 and AEP were overexpressed in human breast neoplasms and correlated with poor prognosis. Patients with low AEP/TRAF6 expression survived for a mean of 111 months (95% confidence interval [CI] = 108 to 115 months), whereas those with high AEP/TRAF6 expression survived for a mean of only 61 months (95% CI = 42 to 79 months; P < .001). CONCLUSIONS Our study elucidates a novel mechanism of AEP regulation and an alternative oncogenic pathway for TRAF6 in breast cancer, which suggests that AEP and TRAF6 protein levels may have prognostic implications in breast cancer patients. Thus, AEP may serve as a biomarker as well as new therapeutic target.

Synthesis of dialkyl cyanoboronates and their application in palladium-catalyzed cyanation of aryl halides

Abstract A new type of cyanoboronate 4 was prepared and used as a new cyano group source in palladium-catalyzed cyanations of aryl and heteroaryl halides to afford the corresponding aryl and heteroaryl nitriles.