Lactams are cyclic amides that are indispensable as drugs and as drug candidates. Conventionall actamization includes acid-mediated and coupling-agent-mediated approaches that suffer from narrow substrate scope,m uch waste, and/orh igh cost. Inexpensive, less-wasteful approaches mediated by highly electrophilic reagents are attractive, but there is an imminent risk of side reactions. Herein,amethods using highly electrophilic triphosgene in am icroflow reactor that accomplishesr apid (0.5-10s), mild, inexpensive, and less-wasteful lactamizationare described. Methods Aa nd B, which use N-methylmorpholine and Nmethylimidazole, respectively, were developed. Various lactams and ac yclic peptide containing acid-and/orh eat-labile functional groups were synthesized in good to high yields without the need for tedious purification. Undesired reactions were successfully suppressed, and the risk of handling triphosgene was minimizedb yt he use of microflow technology.
The properties of butadiene–acrylonitrile copolymers were compared with those of polybutadiene–polyacrylonitrile blends. Also, the properties of copolymers having an acrylonitrile unit content of about 30% were compared with those of polymer blends having the same acrylonitrile unit content, i.e., NBR–NBR, polybutadiene–NBR, and polyacrylonitrile–NBR, having different acrylonitrile unit contents. These blends were prepared by roll blending and the vulcanizates were prepared by sulfur cure. The properties of the copolymers were markedly different from those of the blends, that is, in the blends the properties showed a linear relationship with their blending ratios, while in the copolymers the properties showed a curvilinear relationship. In the cases of the polymer blends having a constant acrylonitrile unit content, those blends which were prepared by blending two polymers having similar acrylonitrile unit contents showed better properties than the ones having very different acrylonitrile unit contents.
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