Synthetic Studies toward Lindenane-Type Sesquiterpenoid Dimers

Abstract

The key transformation for the total synthesis of the lindenane sesquiterpenoid dimers is the intermolecular Diels?Alder reaction between two lindenane-type monomers. Herein we report our efforts made on examination of the biogenetic hypothesis and the inverse-electron-demand Diels?Alder (IEDDA) reaction. The combination of Tf2NH/AlMe3 was developed to catalyze the model IEDDA reaction.

Chemistry and bioactivity of lindenane sesquiterpenoids and their oligomers

“…11 To date, furano-LSs have been reported only from the Lindera genus, including lindenenyl acetate (2), 92,93 linderoxide (3), 94 lindenene (4), 95 linderene (5), 5 linderene acetate (6), 92 isodihydrolinderene (7), 5 lindenenone (8), 5 and isolinderoxide (9). 96 Upon oxidation, the furan ring will transfer to the characteristic a,b-unsaturated g-lactone moiety of LSs with D 15(4) (10-40), D 4(5) (41-47), and further oxidation derivatives (48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63), which was also supported by their bio-inspired total synthesis. 97 Strychnistenolide A (10), 86 6a-acetyl-lindenanolide A (11), 86 strychnilactone 2,6-dihydroxyxanthone (12), 98 chlorajapolide F (13), 99 chlojaponilactone G (14), 100 decorone A (15), 20 linderin A (16), 101 linderolide T (30) 102 and onoseriolide acetate (38) 22 all possess a b-orientated lactone ring.…”

“…48,50 Considering their diverse skeletons and strong bioactivities, [5][6][7][8][9][10]44,45,[47][48][49][50] the total synthesis of LSs and their oligomers has also attracted signicant interest from organic chemists, and thus far, complex and bioactive oligomers with seven types of skeletons have been synthesized by several groups. [51][52][53][54] The aforementioned information indicates that signicant progress has been achieved in the last 100 years regarding the chemistry and bioactivity of LSs and their oligomers.…”

Biomimetic Approaches to the Synthesis of Natural Disesquiterpenoids: An Update

“…The structural and pharmacological features of this group of secondary metabolites attracted the attention of organic chemists, inducing numerous efforts to duplicate the efficiency of natural processes under laboratory conditions [68,69]. To date, only three different total syntheses have been published, two by Liu's group and one by Peng's group.…”