描述了四种新的天然存在的远程功能化次级霉菌代谢物酸酐 lad 的首次合成,从 Np-甲苯基柠康酰亚胺 (5) 开始,分三到六步,总产率为 20-65%。三苯基膦-马来酰亚胺加合物 6 与醛 4 的缩合提供了外酰亚胺 7,其在异构化、水解和酰化后在四个步骤中以 54% 的总产率得到曲霉酸 A (Ia)。加合物6与醛15的缩合类似地在两个步骤中提供了所需的酰亚胺17。酰亚胺 17 的酸催化水解直接提供曲霉酸 B (1b),暴露出作为末端乙炔存在的潜在甲基酮。硼氢化钠诱导曲霉酸 B (1b) 的化学选择性还原产生曲霉酸 C (1c),在乙酸酐诱导的酰化作用下,提供曲霉酸 D (1d)。曲霉酸 C (1c) 的简便 Amano PS 催化酰化以良好的收率得到所需的 (+)-曲霉酸 C (1e) 在 70% ee 中和 (-)-曲霉酸 D (If) 在 72% ee . 在目前的酶促反应中,酸酐部分
Herein developed mercuric triflate-TMU catalyzed hydration of terminalalkyne is a mild procedure to give methyl ketone in excellent yield with high chemoselectivity. By using 0.05 eq of Hg(OTf)2·(TMU)2 and 3 eq of water, hydration takes place at a reasonable rate in acetonitrile.
Reversible S-palmitoylation is an important post-translational modification that regulates the trafficking, localization, and activity of proteins. Cysteine-rich Asp-His-His-Cys (DHHC) domain-containing enzymes are evolutionarily conserved protein palmitoyl acyltransferases (PATs). The human genome encodes 23 DHHC-PATs that regulate diverse cellular functions. Although chemical probes and proteomic methods to detect palmitoylated protein substrates have been reported, no probes for direct detection of the activity of PATs are available. Here we report the synthesis and characterization of 2-bromohexadec-15-ynoic acid and 2-bromooctadec-17-ynoic acid, which are analogues of 2-bromopalmitate (2-BP), as activity-based probes for PATs as well as other palmitoylating and 2-BP-binding enzymes. These probes will serve as new chemical tools for activity-based protein profiling to explore PATs, to dissect the functions of PATs in cell signaling and diseases, and to facilitate the identification of their inhibitors.
Endothelial activation and dysfunction are hallmarks of inflammation. Neutrophil-vascular endothelium interactions have significant effects on vascular wall physiology and pathology. Myeloperoxidase (MPO)-derived products released from activated neutrophils can mediate the inflammatory response and contribute to endothelial dysfunction. 2-Chlorofatty aldehyde (2-ClFALD) is the direct oxidation product of MPO-derived hypochlorous acid (HOCl) targeting plasmalogen phospholipids. The role of 2-ClFALD in endothelial dysfunction is poorly understood and may be dependent on the vascular bed. This study compared the role of 2-ClFALD in eliciting endothelial dysfunction in human coronary artery endothelial cells (HCAEC), human lung microvascular endothelial cells (HLMVEC), and human kidney endothelial cells (HKEC). Profound increases in selectin surface expression as well as ICAM-1 and VCAM-1 surface expression were observed in HCAEC and HLMVEC. The surface expression of these adherence molecules resulted in robust adherence of neutrophils and platelets to 2-ClFALD treated endothelial cells. In contrast to HCAEC and HLMVEC, 2-ClFALD-treated HKEC had substantially reduced adherence molecule surface expression with no resulting increase in platelet adherence. 2-ClFALD-treated HKEC did have an increase in neutrophil adherence. All three endothelial cell lines treated with 2-ClFALD displayed a time-dependent loss of barrier function. Further studies revealed 2-ClHDyA localizes to ER and Golgi when using a synthetic alkyne analog of 2-ClFALD in HCAEC and HLMVEC. These findings indicate 2-ClFALDs promote endothelial cell dysfunction with disparate degrees of responsiveness depending on the vascular bed of origin.
Macrocyclization of Fischer Carbene Complexes as an Approach to Cyclophanes