Different from electronically matched 1,4- and 1,6-additions, herein, we disclose an electronically mismatched 1,5-conjugate addition process with oximes as the nucleophiles. By this design, the oxime moieties are readily introduced to the gamma-position of the electron-deficient substrates in good yields, excellent regioselectivities, and high enantioselectivities. The corresponding allyl oximes are also conveniently transformed into a series of valuable enantioenriched skeletons.

Silyl cobalt species are putative intermediates in cobalt-catalyzed transformations of hydrosilanes. However, their reactivity has remained poorly understood. Reported here is the investigation on four-coordinate disilyl Co(II) complexes with N-hetereocyclic carbene ligation. The reactions of [(ICy)2Co(vtms)] (ICy = 1,3-dicyclohexylimidazol-2-ylidene, vtms = vinyltrimethylsilane) with primary and secondary hydrosilanes (3 equiv.) furnish the four-coordinate disilyl complexes [ trans (ICy)2Co(SiHRR ')2] (SiHRR ' = SiH2Mes, 1 ; SiH2Ph, 2 ; SiH2Cy, 3 ; SiHPh2, 4 ; SiHEt2, 5 ) in moderate to good yields. The structures of 1 , 2 and 4 were established by single-crystal X-ray diffraction. Solution magnetic susceptibility measurement and EPR spectroscopy indicate their low-spin nature ( S = 1/2). Reactivity studies on 4 led to the establishment of the conversions of 4 to the disilyl dihydride Co(III) complex [K(THF)][(ICy)2Co(H)2(SiHPh2)2]n ( 6 ) and the fluorosilyl Co(II) complex [(ICy)2Co(THF)(SiFPh2)][BF4] ( 7 ) when 4 was treated with excess amount of K and AgBF4, respectively, in THF. These conversions hint at the high activity of low-valent and high-valent disilyl cobalt species [trans-(ICy)2Co(SiHPh2)2]1- and [trans-(ICy)2Co(SiHPh2)2]2 +. Complex 4 is reactive toward terminal alkynes, but inert toward alkenes and internal alkynes. The reactions of 4 with terminal alkynes CyC=CH and Me3SiC=CH (3 equiv.) yield the Co(II) complexes [(ICy)2Co(C=CCy)2] ( 8 ) and [(ICy)2Co(C=CSiMe3)((SiMe3)C= CH2)] ( 9 ), respectively, along with H2SiPh2 and alkynylsilanes RC=CSiHPh2 (R = Cy, SiMe3), whereas the reaction with 4-CF3C6H4C=CH (3 equiv.) produce [(ICy)2Co(C=CAr)((Ar)C= CH(SiHPh2)C= CHAr)] (Ar = 4-CF3C6H4) ( 10 ) and H2SiPh2. These reactions are proposed to involve sigma-bond metathesis reactions between alkyne C(sp)-H bonds and Co-Si bonds in 4 . Complexes 6 -10 have been characterized by NMR spectroscopy, X-ray diffraction study, and elemental analysis.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Fusarium species are able to produce structurally diverse secondary metabolites which exhibit different biological functions. Based on the epigenetic research strategy, the global negative regulator, kmt6 gene, which is related to the expression of the secondary metabolite gene cluster, was knocked out to activate the silent gene. A chemical investigation on the cultures extract of the mutant strain led to the isolation of compounds 1 similar to 4. Among them, fusarane B (1) and fusarane C (2) are two new compounds. Furthermore, the antitumor activities of 1 similar to 4 were assayed. Compounds 1 and 3 exhibited moderate inhibitory effect on two human cancer cells of Hela and Mia PaCa2. In addition, the biosynthetic pathways of two polyketones 2 and 4 were proposed based on in vivo examination and molecular docking experiment.

Silicon-stereogenic organosilanes have attracted heightened atten-tion in various scientific communities including synthetic chemistry, material chemistry, and medicinal chemistry, along with the rapid developments in the catalytic construction of various Si-stereogenic architectures more recently. This review offers a comprehensive overview of catalytic preparation of Si-stereogenic organosilanes by categorizing prochiral starting materials (such as dihydrosilanes, dialkylsilanes, diarylsilanes, dialkenylsilanes, dialkynylsilanes, and other precursors).

Polypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water-soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full-spectrum solar-light-driven H2 production within a supramolecular system built by the co-assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 mu mol h(-1) g(-1) over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H-2 production rate of >51,700 mu mol h(-1) g(-1) with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self-assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self-assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.