Synthesis and activity of potent 3-(isoxazolidin-5-yl)- and 3-(isoxazolidinium-5-yl)cephalosporins

Stereoselective Synthesis of Isoxazolidines via Copper-Catalyzed Alkene Diamination

A convenient copper-catalyzed intramolecular/intermolecular alkene diamination reaction to synthesize 3-aminomethyl-functionalized isoxazolidines under mild reaction conditions and with generally high levels of diastereoselectivity was achieved. This reaction demonstrates that previously underutilized unsaturated carbamates are good [Cu]-catalyzed diamination substrates. Sulfonamides, anilines, benzamide, morpholine, and piperidine can serve as the external amine source. This relatively broad amine range is attributed to the mild reaction conditions. Reduction of the N-O bond could also be achieved, revealing the corresponding 3,4-diamino-1-alcohols efficiently.

A 3-Vinyl Cephem Derivative, a Useful Intermediate in the Synthesis of Cepham Antibiotics, from Aspergillus awamori Associated with Banana Fruit

Aspergillus awamori was isolated from a diseased banana fruit, Musa acuminata cv. Ambul. The fungus was fermented in potato dextrose broth and on potato dextrose agar media and the fungal media were extracted with EtOAc. Chromatographic separation of the EtOAc extracts furnished 4-methoxybenzyl 7-phenylacetamido-3-vinyl-3-cephem-4-carboxylate (1), along with three naphtho-γ-pyrones, flavasperone (2), foncesinone A (3) and aurasperone A (4), and three alkaloids, aspernigrin A (5), pestalamide C (6) and nigragillin (7). Compound 1, a known key intermediate in the chemical synthesis of cepham antibiotics, was isolated from a natural source for the first time. Compound 1 is the first 3-vinyl cephem derivative of microbial origin.