Simple construction of bicyclo[4.3.0]nonane, bicyclo[3.3.0]octane, and related benzo derivatives by palladium-catalyzed cycloalkenylation.

Reaction of 3-butenyl beta-keto esters or 3-butenyl alpha-aryl ketones with a catalytic amount of [PdCl2(CH3CN)2] (2) and a stoichiometric amount of Me3SiCl or Me3SiCl/CuCl2 in dioxane at 25-70 degrees C formed 2-substituted cyclohexanones in good yield with high regioselectivity. This protocol tolerated a number of ester and aryl groups and tolerated substitution at the allylic, enolic, and cis and trans terminal olefinic positions. In situ NMR experiments indicated that the chlorosilane was not directly involved in palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70 degrees C.

Palladium-Catalyzed Intramolecular Hydroalkylation of Alkenyl- β-Keto Esters, α-Aryl Ketones, and Alkyl Ketones in the Presence of Me3SiCl or HCl

Total synthesis of aphidicolane and stemodane diterpenes

Transition metals in organic synthesis highlights for the year 1994

The 8-epiaphidicolane skeleton (3) was formed in one key reaction by highly diastereoselective tandem transannular Diels−Alder (TADA)−aldol reactions from the trans-trans-cis trienic macrocycle (4). The unnatural derivative (11R)-(−)-8-epi-11-hydroxyaphidicolin (2) was thus constructed, and an original solution to the C16 functionalization problem of many aphidicolin (1) syntheses is presented.

New approach to aphidicolin and total asymmetric synthesis of unnatural (11R)-(-)-8-epi-11-hydroxyaphidicolin by tandem transannular Diels-Alder/aldol reactions.

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

Pd2+-promoted cyclization in tetracyclic diterpene synthesis highly diastereoselective formal total synthesis of (±)-stemodin

Aphidicolin synthesis (I)—formal synthesis of (±)-aphidicolin by the successive intramolecular Diels-Alder reactions

Synthetic approach to stemodin (I) — a novel stereocontrolled construction of the stemodane system by the successive intramolecular Diels-Alder reactions

Pd(II)-Promoted Cyclization in Tetracyclic Diterpene Synthesis. Highly Diastereoselective Formal Total Synthesis of (.+-.)-Stemodin.

Takashi Seishi

Papers

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

Pd2+-promoted cyclization in tetracyclic diterpene synthesis highly diastereoselective formal total synthesis of (±)-stemodin

Aphidicolin synthesis (I)—formal synthesis of (±)-aphidicolin by the successive intramolecular Diels-Alder reactions

Synthetic approach to stemodin (I) — a novel stereocontrolled construction of the stemodane system by the successive intramolecular Diels-Alder reactions

Pd(II)-Promoted Cyclization in Tetracyclic Diterpene Synthesis. Highly Diastereoselective Formal Total Synthesis of (.+-.)-Stemodin.