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Six Ring Oxygen Systems

Norlignans are a small group of natural products of which sequirin (76) is a typical example. A multistage synthesis of the racemic ether (77) has now been described, the key step being the stereospecific ring closure of (75) to (77) using [Pg.213]

Ficini, J. Besseyre, and A. Krief, Bull. Soc. chim. France, Part 2, 1976, 987. F. Cooke and P. Magnus, J.C.S. Chem. Comm., 1976, 519. [Pg.213]

The double ring-closure of the diazoketone (81) with phenyl acetylene gave (82) in a remarkable 86% yield the reaction was catalysed by cupric acetoacetonate and [Pg.216]

Syntheses of oxygen-containing natural products have employed some interesting transformations. The total synthesis of pederamide (94), the main hydrolysis product of the powerful insect poison pederin, has utilized two key ring-forming [Pg.216]

Motoyama, and M. Hamaguchi, Bull. Chem. Soc. Japan, 1976, 49, 2298. [Pg.216]


Six Ring Oxygen Systems.—Ynamines add to cisoid-enones to give good yields of amino-y-pyrans and pyranopyrans (Scheme 28). Alkylation of the monoanion... [Pg.213]




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