Stereoselective synthesis of (5S,6S)- and (5S,6R)-aza-muricatacin from an l-glutamic acid derivative

Rapid and Mild Lactamization Using Highly Electrophilic Triphosgene in a Microflow Reactor

Lactams are cyclic amides that are indispensable as drugs and as drug candidates. Conventional lactamization includes acid-mediated and coupling-agent-mediated approaches that suffer from narrow substrate scope, much waste, and/or high cost. Inexpensive, less-wasteful approaches mediated by highly electrophilic reagents are attractive, but there is an imminent risk of side reactions. Herein, a methods using highly electrophilic triphosgene in a microflow reactor that accomplishes rapid (0.5-10 s), mild, inexpensive, and less-wasteful lactamization are described. Methods A and B, which use N-methylmorpholine and N-methylimidazole, respectively, were developed. Various lactams and a cyclic peptide containing acid- and/or heat-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 minimized by the use of microflow technology.

Blaise reaction: synthesis, skeletal diversification of C(4) substituted 5-ylidenepyrrol-(5H)-ones and the role of the strategically located ester on the reactivity of the nitriles

We have achieved a simple and convenient synthesis of several C(4) substituted 5-ylidenepyrrol-(5H)-ones from 3-aryl/heteroaryl/alkyl 3-cyanopropionates and ethyl/methyl bromoacetates via a useful variation of the classical Blaise reaction.

Novel Isoxazolidine and γ-Lactam Analogues of Homonucleosides

Homonucleoside analogues cis-16 and trans-17 having a (5-methoxycarbonyl)isoxazolidine framework were synthesized via the 1,3-dipolar cycloaddition of nucleobase-derived nitrones with methyl acrylate. Hydrogenolysis of the isoxazolidines containing thymine, dihydrouracil, theophylline and adenine moieties efficiently led to the formation of the respective γ-lactam analogues. γ-Lactam analogues having 5-bromouracil and 5-chlorouracil fragments were synthesized by treatment of uracil-containing γ-lactams with NBS and NCS. Isoxazolidine and γ-lactam analogues of homonucleosides obtained herein were evaluated for activity against a broad range of DNA and RNA viruses. None of the compounds that were tested exhibited antiviral or cytotoxic activity at concentrations up to 100 µM. The cytostatic activities of all compounds toward nine cancerous cell lines was tested. γ-Lactams trans-15e (Cl-Ura) and cis-15h (Theo) appeared the most active toward pancreatic adenocarcinoma cells (Capan-1), showing IC50 values 21.5 and 18.2 µM, respectively. Isoxazolidine cis-15e (Cl-Ura) inhibited the proliferation of colorectal carcinoma (HCT-116).

Biologically active γ-lactams: synthesis and natural sources

The γ-lactam moiety is present in a large number of natural and non-natural biologically active compounds. The range of biological activities covered by these compounds is very broad. Functionalized γ-lactams are thus of high interest and have great potential in medicinal chemistry. This review provides a description of the title compounds by focusing on their synthesis, natural sources and biological activities.

Synthesis and antitumour activity of new muricatacin and goniofufurone analogues

A divergent approach to the 7-oxa (-)-muricatacin analogue 2, the corresponding (+)-enantiomer ent-2 and the furanolactone 3 is reported starting from D-xylose. The resulting lactones have shown a potent and selective in vitro cytotoxicity against certain human neoplastic cell lines.