Mitsuaki Kodama

Total synthesis of (±)-silphinene

Abstract The regio- and stereoselective total synthesis of (±)-silphinene, an angular tricyclopentanoid sesquiterpene, was achieved starting from dicyclopentadiene.

Synthesis of macrocyclic terpenoids by intramolecular cyclization VII. Total synthesis of (±)-cubitene

Abstract Stereoselective total synthesis of (±)-cubitene, a diterpene isolated from termite soldiers, and its stereisomer has been achieved utilizing the anion-induced intramolecular cyclization.

Synthesis of macrocyclic terpenoids by intramolecular cyclization VI. Synthesis of 3Z-cembrene A and cembrenene

Abstract Two 14-membered diterpenes, 3Z-cembrene A and cembrenene, isolated from a termite and a soft coral, respectively, were synthesized by the anion-induced cyclization of geranylgeranyl phenyl sulfide.

Synthesis of macrocyclic terpenoids by intramolecular cyclization XIII. : Stereoselective synthesis of (±)-cubitene, a component of defense secretion of termites

Abstract Stereoselective synthesis of cubitene ( 1 ), a novel diterpene isolated from defense secretion of termites, has been accomplished using an intramolecular reaction of α-sulfenyl carbanion with epoxide. Hydride reduction of the ketone 11 obtained by Claisen rearrangement occurred in unexpectedly high stereoselectivity yielding the chlorohydrin 12 with the desired stereochemistry.

Synthesis of macrocyclic terpenoids by intramolecular cyclization IX. Total synthesis of (±)-obscuronatin and (±)-biflora-4,10(19),15-triene.

Abstract Stereoselective total synthesis of (±)-obscuronatin, a marine diterpene with a 10-membered ring, has been achieved utilizing the anion-induced cyclization of an acyclic epoxy sulfide. The synthesis confirmed the stereostructure of the natural product.

Biomimetic transformations of germacradienes. Stereospecific conversion of hedycaryol phenyl sulfides to cadinanes

Abstract E,E- and 2Z,6E-hedycaryol phenyl sulfides were converted by [2.3]sigmatropy of their sulfoxides to the same allyl alcohol which in turn afforded cadinane derivatives stereospecifically by the action of acids.

Synthesis of macrocyclic terpenoids by intramolecular cyclization V. transannular reactions of hedycaryol isomers

Abstract Thermal rearrangement and acid-catalyzed cyclization of all possible geometrical isomers of hedycaryol were investigated. From the stereochemistry of the products, the reacting conformations were deduced. While three (E,E-, E,Z- AND Z,E-) isomers reacted through the crossed conformations, Z,Z-isomer yielded products via parallel conformations. The thermal reaction at higher temperatures revealed the additional pathways involving Cope rearrangement of elemols. All possible stereoisomers of elemol were synthesized. The structure of “epielemol” has to be revised.

Stereoselective total synthesis of bazzanene

Abstract 3azzanene, the stereoisomer of trichodiene, isolated from a liverwort was synthesized with complete stereoselectivity in 8 steps (12% yield) starting from a known bicyclo[2.2.2]octane derivative.

Structure and absolute configuration of α-kessyl alcohol and kessyl glycol

Abstract The structures and absolute configuration of α-kessyl alcohol (I) and kessyl glycol (II), sesquiterpenic constituents of Japanese valerian roots, have been established on the basis of chemical and spectroscopic data.

Synthesis of macrocyclic terpenoids by intramolecular cyclization VIII. synthesis o cembra-3E, 7E, 11E, 15(17)-tetraen-trans-16, 2-olide

Abstract A synthesis of the naturally-occurring title compound has been accomplished. It represents the first success in the synthesis of the naturally-occurring cembranolides.