Enantioselective Total Synthesis and Assignment of the Absolute Configuration of the Meroterpenoid (+)-Taondiol.

The first enantioselective total synthesis of (+)-taondiol, a pentacyclic marine meroterpenoid, has been achieved, which in addition to confirming the structure also established the absolute configuration of the natural product. The notable points in the synthetic route are synthesis of a highly functionalized tricyclic diterpenoid moiety starting from an enantiopure Wieland-Miescher ketone derivative in concise manner via Robinson-type annulation and an elegant hydrogen atom transfer olefin reduction followed by Lewis acid-catalyzed Friedel-Crafts reaction for one-pot C-C and C-O bond formations resulting in construction of the pentacyclic meroterpenoid skeleton.

Biomimetic Enantioselective Total Synthesis of (-)-Mycoleptodiscin A.

Biomimetic total synthesis of (-)-mycoleptodiscin A (1) was achieved starting from the enantiopure key intermediate, which was prepared by Friedel-Crafts reaction between 7-methoxyindole and chiral primary allylic alcohol. The crucial step in this synthesis was an intramolecular Friedel-Crafts reaction at C-4 of the indole derivative driven by the EDG/EWG within a compound that was rationally designed to prevent the cyclization reaction at the C-2 positon of indole, thereby successfully providing the complete carbon framework of 1. This intramolecular Friedel-Crafts reaction at C-4 of indole derivative could be applied for the synthesis of other C-4-substituted indole alkaloid natural products.

Enantiospecific total syntheses and assignment of absolute configuration of cannabinol-skeletal carbazole alkaloids murrayamines-O and -P.

First enantiospecific total syntheses of the cannabinol-skeletal carbazole alkaloids murrayamines-O and -P isolated from root barks of Murraya euchrestifoli, have been accomplished by highly diastereoselective, Lewis acid catalyzed coupling reactions of commercially available monoterpenes with carbazole derivative, which in addition to confirming the structure also established the absolute configuration of the natural products. Synthesis of both natural products and their enantiomers was achieved with high atom economy, in a protecting-group free manner and in six steps longest linear sequence from commercially available aniline derivative and verbenol.

Protecting group free enantiospecific total syntheses of structurally diverse natural products of the tetrahydrocannabinoid family.

A simple, highly diastereoselective, Lewis acid catalyzed Friedel-Crafts coupling of a cyclic allylic alcohol with resorcinol derivatives has been developed. The method was applied for the enantiospecific total syntheses of structurally diverse natural products such as machaeriol-D, Δ(8)-THC, Δ(9)-THC, epi-perrottetinene and their analogues. Synthesis of both natural products and their enantiomers has been achieved with high atom economy, in a protecting group free manner and in less than 6 steps, the longest linear sequence, in a very good overall yield starting from R-(+) and S-(-)-limonene.