Synthesis and evaluation of novel analogues of ripostatins.

Ripostatins are polyene macrolactones isolated from the myxobacterium Sorangium cellulosum. They exhibit antibiotic activity by inhibiting bacterial RNA polymerase (RNAP) through a binding site and mechanism that are different from those of current antibacterial drugs. Thus, the ripostatins serve as starting points for the development of new anti-infective agents with a novel mode of action. In this work, several derivatives of ripostatins were produced. 15-Desoxyripostatin A was synthesized by using a one-pot carboalumination/cross-coupling. 5,6-Dihydroripostatin A was constructed by utilizing an intramolecular Suzuki cross-coupling macrolactonization approach. 14,14'-Difluororipostatin A and both epimeric 14,14'-difluororipostatins B were synthesized by using a Reformatsky type aldol addition of a haloketone, Stille cross-coupling, and ring-closing metathesis. The RNAP-inhibitory and antibacterial activities are presented. Structure-activity relationships indicate that the monocyclic keto-ol form of ripostatin A is the active form of ripostatin A, that the ripostatin C5-C6 unsaturation is important for activity, and that C14 geminal difluorination of ripostatin B results in no loss of activity.

Total synthesis of RNA-polymerase inhibitor ripostatin B and 15-deoxyripostatin A.

Keep me skipped: a highly convergent total synthesis of ripostatin B, an inhibitor of the bacterial RNA polymerase, is described. The key steps to construct and avoid isomerization of the skipped triene are a double Stille cross-coupling reaction and a ring-closing metathesis. Furthermore, 15-deoxyripostatin A, a stable and conformationally locked analogue of ripostatin A, was prepared and tested in vivo.

The Psychology Analysis for Post-production of College Students' Short Video Communication Education Based on Virtual Image and Internet of Things.

To improve the understanding of film and television postproduction for college students in the era of intelligent media, a study is conducted on college students' short video communication education and audience psychology based on the rapid development of virtual image and the Internet of Things (IoT). Primarily, the collaborative filtering algorithm (CFA) is optimized and combined with the principle of Spark and Hadoop platforms as well as the IoT and virtual image technologies. Then, a hybrid computing model is proposed, and the two algorithms are improved and combined, with 90,000 network video records as data samples. Finally, the push accuracy of the hybrid algorithm and the traditional algorithm is calculated and compared, and based on this, a questionnaire survey on the audience psychology of short video production is carried out for college students. The results show that the time user of the combined algorithm is always at least 0.4 s faster than that of a single algorithm and the running speed of the algorithm with five nodes is nearly 80% higher than the algorithm with a single node. The Spark algorithm with multinode has good versatility in image recording and processing of large groups of college students. When processing more than 100,000 image records, the deviation values of Spark and Hadoop with a single node exceeded 1.1, but the deviation value of the hybrid algorithm was still lower than 1.1. With the increase of data volume, the deviation values of the three algorithms are increasing. Compared with the traditional CFA algorithm, the optimized algorithm has a higher speed in processing data and is more accurate in content pushing. From the questionnaire survey of college students, it is found that contemporary college students are not active in learning knowledge of virtual images. Hence, it is concluded that colleges must carry out relevant courses based on short video communication education and strengthen the short video communication education of college students. A reference is provided for the development of college students' short video communication education in the digital age.

Total synthesis of ripostatin A.

The first total synthesis of the bacterial RNA-polymerase inhibitor ripostatin A (1) was achieved. The route utilizes a cyclic methyl acetal intermediate and a sequence of a double Stille cross-coupling reaction followed by a ring-closing metathesis for the construction of the macrolactone ring. Additionally, an unprecedented formation of the 4-methoxy substituted tetrahydropyrans was observed during the acid catalyzed acetalization of the ß,δ-dihydroxyketone.