The total synthesis of (+)-ryanodol (1) is described.

An asymmetric total synthesis of (+)-chatancin was achieved via a transannular Diels-Alder (TADA) reaction of an in situ generated macrocyclic pyranophane pseudobase. The presented route constitutes the second of two proposed biosynthetic pathways that involves a TADA reaction. It links this diterpene biogenetically to the cembranoids. A set of TADA selection rules that rationalize the formation of (+)-chatancin from a dynamic equilibrium of four 2-hydroxy-2H-pyrane bicycles and their 16 potential TADA transition states are also outlined. Beyond the TADA reaction, highlights of the synthetic work include the assembly of a chiral acyclic macrocyclization substrate from (S)-citronellol and an efficient macrocyclization via a beta-ketosulfoxyde/enone Michael addition.

Ceric ammonium nitrate oxidation of cyclohexanone, cyclopentanone, and norbornanone gives nitratocarboxylic acids, oxidation of adamantanone and adamantan-2-01 gives the lactone 14.Par oxydation avec le nitrate ckrique d'ammonium, la cyclohexanone, la cyclopentanone, et la norbornanone donnent des acides nitrato-carboxyliques correspondants. L'oxydation de l'adamantanone ou de I'adamantanol-2 conduit a la lactone 14 correspondante.

Treatment of vinyl acetate with ozone yields the mixed anhydride of acetic and formic acids and formaldehyde oxide. The formaldehyde oxide can be trapped by reaction with ketones yielding the corresponding ozonides. Thermal decomposition of these ozonides gave the corresponding lactone and (or) the corresponding olefin carboxylic acid. The ozonides were also prepared by the ozonolysis of the corresponding olefins.

This paper reports the transformation of (+)-anhydroryanodol (6) to (+)-ryanodol (7) by reductive cyclization of lactone epoxide derivatives 9 and 20 (Scheme 4). Keywords: anhydroryanodol, ryanodol, diterpene, synthesis, reductive cyclization.