Phosphorus dendrimer immobilized azabis(oxazoline) ligands can be efficiently synthesized up to the third generation with 48 ligand molecules being attached to the periphery using click chemistry. The so-assembled macromolecules were evaluated in copper(II)-catalyzed asymmetric benzoylations, showing good yields and enantioselectivities. Moreover, the copper(II)-catalysts could be readily recovered
B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>‐Catalyzed [2+3]‐Cyclative <i>o</i>,<i>m</i>‐diC‐H Functionalization of Phenols
作者:Jingyan Luo、Zhou Luo、Biqi Zhang、Qiuyu Zhao、Lu Liu、Yuanyuan Liu
DOI:10.1002/chem.202301595
日期:2023.12.19
B(C6F5)3-catalyzed highly chemoselective [2+3]-cyclative diC−H functionalization of phenols tethered with propargylic ether motifs was developed for the synthesis of polycyclic compounds. Derivatizations of the phenol-OH group demonstrated the good variability of the cyclization products, indicating the potential application of this methodology in the preparation of other types of polycyclic compounds.
AB(C 6 F 5 ) 3催化的与炔丙基醚基序相连的酚的高度化学选择性的[2+3]-环化二C−H官能化被开发用于多环化合物的合成。酚-OH基团的衍生化证明了环化产物具有良好的可变性,表明该方法在制备其他类型的多环化合物中具有潜在的应用前景。
TX-2152: A conformationally rigid and electron-rich diyne analogue of FTY720 with in vivo antiangiogenic activity
We designed FTY720 analogues with conformationally rigid and electron-rich acetylenic chains as anti-angiogenic agents ( the monoyne 1: TX-2148, the diyne 2: TX-2152, the triyne 3: TX-2256). Molecular orbital ( MO) calculations of our designed acetylenic analogues and FTY720 showed that the localization of the lowest unoccupied MO and the highest occupied MO increased from phenyl ring to acetylenic chain compared with that of FTY720. These acetylenic analogues were synthesized from p-hydroxyphenylethanol as a starting material. The construction of the acetylenic chain was carried out by an iterative strategy using a Sonogashira cross-coupling reaction and desilylative bromination in two steps. The corresponding overall yields of the monoyne 1, the diyne 2, and the triyne 3 were 27% ( 11 steps), 13% ( 13 steps), and 10% ( 15 steps). The in vivo antiangiogenic activities of these acetylenic analogues and FTY720 were evaluated by the chick embryo chorioallantoic membrane ( CAM) assay and compared to the activities of the known antiangiogenic agent TNP-470. The diyne 2 showed more potent antiangiogenic activity ( 90% inhibition) than FTY720 ( 77% inhibition) and other acetylenic analogues ( the monoyne 1: 42% inhibition, the triyne 3: 60% inhibition), and TNP-470 ( 82% inhibition) at a dose of 10 mu g/CAM, without showing toxicity. The diyne 2 also had potent inhibitory activity at a dose of 5 and 2.5 mu g/CAM. These results indicate that the flexibility of C8 alkyl chain of FTY720 is not required for its antiangiogenic activity. We suggest that the diyne 2 ( TX-2152) may be a promising candidate as an antiangiogenic agent for antineoplastic drug discovery. (C) 2008 Elsevier Ltd. All rights reserved.
Stereoselective synthesis of bioactive natural spiroacetals aculeatins A and B
The stereoselective synthesis of two naturally occurring bioactive spiroacetals, aculeatins A and B has been accomplished using 1-tetradecanal as the starting material. The sequence introduces diastereoselective iodine-induced electrophilic cyclization and ring opening of epoxide with 1,3-dithiane as the key steps. (C) 2010 Elsevier Ltd. All rights reserved.