Synthesis of 3-substituted quinolin-2(1H)-ones via the cyclization of o-alkynylisocyanobenzenes.

A facile synthesis of various functionalized 3-substituted quinolin-2(1H)-ones through Ag(i) nitrate-catalyzed cyclization of o-alkynylisocyanobenzenes is described. The reaction allows rapid and convenient access to 3-substituted quinolin-2(1H)-one scaffolds in moderate to good yields.

Immobilized chitinase as effective biocatalytic platform for producing bioactive di-N-acetyl chitobiose from recycled chitin food waste.

Described is chitinase immobilization on magnetic nanoparticles (MNPs) as biocompatible support for enzymatic production of di-N-acetyl chitobiose from chitin waste. Chitinase immobilization was feasible with an immobilization yield of 88.9 ± 1.6 % with 97.8 ± 1.0 % retention of activity and compared to free enzyme work, immobilization conferred better thermal and storage stability. As practical benefit the attachment to magnetic nanocarriers enabled easy enzyme recovery after repeated application runs and thus sustainable reuse. In fixed state chitinase retained a remarkable 39.7 ± 2.6 % of the starting activity after 16 reaction cycles. Furthermore, immobilized chitinase showed higher catalytic activity than free chitinase in converting shrimp shells and squid-pens chitins into di-N-acetyl chitobiose in a single-step reaction. The final yield of purified compound was 37.0 ± 1.2 % from shrimp shells and 61.1 ± 0.5 % from squid-pens chitin. In conclusion, an efficient MNP-based chitinase immobilization system with the potential for large-scale production was developed.