Masahiro Toyota

Stereocontrolled construction of a spiro fused bicyclo[2.2.2]Octane ring system by the intramolecular double michael reaction

Abstract The lithium enolate from the cyclohexenone (8) possessing the α, β-unsaturated ester moiety caused an intramolecular double Michael reaction to produce stereoselectively the spiro fused bicyclo[2.2.2]-octane (10).

Construction of bicyclo[2.2.2]octane ring system via homoallyl-homoallyl radical rearrangement

Abstract We designed a sequential three-step, one-pot reaction (homoallyl-homoallyl radical rearrangement reaction) to generate highly functionalized bicyclo[2.2.2]octane ring system, and succeeded in developing a novel synthetic method to bicyclo[2.2.2]octane compounds from simple cyclohexene derivatives.

Total Synthesis of (±)-Hirsutene via Pd2+-Promoted Cycloalkenylation Reaction

Abstract Beginning with trans -2-methyl-4-cyclohexenecarboxylic acid ( 9 ), a total synthesis of linear triquinane sesquiterpene (±)-hirsutene ( 1 ) has been accomplished. An acid catalyzed intramolecular conjugate addition ( 7→6a ) and a Pd 2+ -promoted highly stereocontrolled cyclization ( 5→4 ) were utilized for the key step of the sequence. Interestingly, some synthetic intermediates exhibited cytotoxicity.

Intramolecular double Michael reaction. III: Stereoselective chiral synthesis of atisiran-15-one

Abstract Atisiran-15-one (5) was stereoselectively synthesized starting from the ketone (10) through the intramolecular double Michael reaction.

Intramolecular double Michael reaction. Part II. Synthesis of isoatisirene type compound

Abstract Intramolecular double Michael reaction of the α,β-unsaturated enone ester (16), prepared from the dienone (5), stereoselectively gave the tetracyclic product (17), which was converted into the isoatisirene type compound (20).

A novel synthesis of the basic carbon framework of fredericamycin A. Promising routes for the spiro chiral center construction of the CD-ring system

Abstract The Intramolecular Diels-Alder reactions of the dienynes readily obtainable from the aromatic aldehydes and ethyl 1-acetylcyclopentane-1-carboxylate, were found to proceed in a highly regioselective manner with formation of the novel title compounds as sole products.

Pd2-promoted cyclization in linear triquinane synthesis total synthesis of (±)-hirsutene

Abstract A sequence leading from trans -6-methyl-3-cyclohexenecarboxylic acid ( 3 ) to the cis, anti, cis - tricyclopentane ring system of the hirsutanes is described in which the key step utilizes an acid catalyzed intramolecular conjugate addition ( 5→6a ) and a Pd 2+ -promoted highly stereocontrolled cyclization ( 7→8 ).

Palladium catalyzed reductive cyclization reaction in alkaloid synthesis — an enantioselective total synthetic route to (+)-pumiliotoxin C

Beginning with the chirally homogeneous cyclohexenol 3, an enantioselective total synthetic route to (+)-pumiliotoxin C (1) has been described. Palladium catalyzed reductive cyclization reaction was employed to prepare a key component in the synthesis.

Stemodin synthesis (II) — highly diastereoselective formal total synthesis of − -stemodin via Pd2+-promoted cycloalkenylation reaction

Abstract Diastereoface-selective Pd 2+ -promoted cycloalkenylation reaction ( 22 → 24 ) has been employed as the key step for a conceptually new and highly diastereocontrolled formal total synthesis of − -stemodin ( 1 ). Interestingly, the synthetic intermediates ( 12 ) and its stereoisomer ( 29 ) exhibited strong cytotoxicity.

Aphidicolin synthesis. II: An expeditious and efficient formal synthesis of (±)-aphidicolin

Abstract An expeditious and efficient formal total synthesis of an antiviral and antitumor tetracyclic diterpene aphidicolin (1) has been achieved. An intramolecular Heck reaction (7→6) and an intramolecular Diels-Alder reaction (4→3) were utilized for the key steps of the sequence.