Stereoselective Total Synthesis of Formosanol, Tsugacetal, and Methyl β-Conidendral

Abstract

The first enantioselective total synthesis of aryltetralin lignan acetals, (−)-formosanol, (+)-tsugacetal, (+)-methyl β-conidendral, and their enantiomers have been accomplished on the basis of the Pd-catalyzed asymmetric allylic cycloaddition as a key step. Six stereoisomers of the lignan acetals have been synthesized via a 7–8 step sequence in up to 14% overall yield. The in vitro cytotoxicity against several cancer cells has preliminarily been examined for the obtained six stereoisomers of lignan acetals.

Recent updates on vinyl cyclopropanes, aziridines and oxiranes: access to heterocyclic scaffolds

“…An appropriately designed tetrahydrofuran 21i accessed from the present strategy has been utilized for the synthesis of lignin-based natural products, such as (−)-formosanol 22 and (+)-tsugacetal 23. 30 The isonucleoside motif has gained profound significance due to its high biological profile. 31 For instance, Tanzisertib 32 has been evaluated for fibrosis treatment, and BMS-181165 33 exhibits potent activity against HSV and VZN.…”

“…An appropriately designed tetrahydrofuran 21i accessed from the present strategy has been utilized for the synthesis of lignin-based natural products, such as (−)-formosanol 22 and (+)-tsugacetal 23 . 30…”

Asymmetric palladium-catalyzed decarboxylative [3 + 2] cycloaddition: straightforward construction of chiral spiro-heterocyclic scaffolds

“…Compared with other strategies, Pd-catalyzed cycloaddition utilizing zwitterionic π–allyl palladium complexes as key intermediates offers a distinctive pathway in organic synthesis to deliver targeted molecules that are challenging to produce using conventional methods. 6 In particular, the versatile α-arylidene, derived from different scaffolds, enables the efficient and rapid synthesis of spiro-heterocycles under palladium catalysis (Scheme 1C). 7 However, the construction of spiro-pyrazolones and pyrazolone-fused spirocyclic analogues from α-arylidene still remains elusive.…”

Synthesis of Chiral 2,3-Dihydrofurans via One-Pot Pd-Catalyzed Asymmetric Allylic Cycloaddition and a Retro-Dieckmann Fragmentation Cascade

“…Most recently, Hou and co-workers disclosed Pd-catalyzed asymmetric allylic cycloaddition of vinyl epoxides with substituted propiolates to access 3,4,5-trisubstituted 2,3-dihydrofurans with high enantioselectivities (Scheme b) . Our group recently developed Pd-catalyzed asymmetric allylic cycloaddition of vinylethylene carbonates (VECs) with various unsaturated electrophiles to rapidly access diverse chiral oxo-heterocycles with high efficiencies . We found that the Pd-catalyzed asymmetric allylic cycloaddition of VECs with 3-cyanochromones can produce furanobenzodihydropyrans bearing three stereocenters with high stereoselectivities .…”