Acylsilanes are of wide interest and have been investigated as an important class of organic reaction intermediates with superior chemical and physical properties. Various synthetic methods for the preparation of acylsilanes with mild reaction conditions resulting in excellent yields and high stereoselectiv-ity have been developed. These strategies mainly include stepwise reaction design, oxidative systems, isomerization/rearrangement, silylation of carboxylic acid derivatives and carbonylation. This minireview summarizes recent advances in the synthesis of acylsilanes over the past decade.

We present herein a highly effective nickel-catalyzed Larock annulations of substituted 2-formylphenyl trifluoromethanesulfonate with alkynes to provide access to a wide range of indenones that are valuable synthetic intermediates for...

Herein, we report a redox-neutral Ni-catalyzed cross-coupling reaction of two readily available precursors to produce the corresponding ketones that are an important structural motif in numerous biologically active entities. By the use of a commercially available nickel/Triphos catalytic system, a range of easily accessible alkenyl primary alcohols and aryltriflates can be converted in a rapidly assembled fashion to valuable ketones with good yields and wide functional group tolerance. We also demonstrate the utility of this transformation by late-stage functionalization of a large set of complex molecules with good efficiency, which offers a distinct entry to more functionalized aromatic ketones.

Background Xylan is the most abundant hemicellulose polysaccharide in nature, which can be converted into high value-added products. However, its recalcitrance to breakdown requires the synergistic action of multiple enzymes. Aspergillus niger, possessing numerous xylan degrading isozyme-encoding genes, are highly effective xylan degraders in xylan-rich habitats. Therefore, it is necessary to explore gene transcription, the mode of action and cooperation mechanism of different xylanase isozymes to further understand the efficient xylan-degradation by A. niger. Results Aspergillus niger An76 encoded a comprehensive set of xylan-degrading enzymes, including five endo-xylanases (one GH10 and four GH11). Quantitative transcriptional analysis showed that three xylanase genes (xynA, xynB and xynC) were up-regulated by xylan substrates, and the order and amount of enzyme secretion differed. Specifically, GH11 xylanases XynA and XynB were initially secreted successively, followed by GH10 xylanase XynC. Biochemical analyses displayed that three GH11 xylanases (XynA, XynB and XynD) showed differences in catalytic performance and product profiles, possibly because of intricate hydrogen bonding between substrates and functional residues in the active site architectures impacted their binding capacity. Among these, XynB had the best performance in the degradation of xylan and XynE had no catalytic activity. Furthermore, XynA and XynB showed synergistic effects during xylan degradation. Conclusions The sequential secretion and different action modes of GH11 xylanases were essential for the efficient xylan degradation by A. niger An76. The elucidation of the degradation mechanisms of these xylanase isozymes further improved our understanding of GH-encoding genes amplification in filamentous fungi and may guide the design of the optimal enzyme cocktails in industrial applications.