First Diastereoselective Synthesis of (−)-Methyl Thyrsiflorin A, (−)-Methyl Thyrsiflorin B Acetate, and (−)-Thyrsiflorin C

Abstract

An efficient procedure for the synthesis of scopadulan diterpenes, using (+)-podocarp-8(14)-en-13-one 13 as starting material, is reported. This procedure has been used for the diastereoselective synthesis of (-)-methyl thyrsiflorin A (8), (-)-methyl thyrsiflorin B acetate (9), and (-)-thyrsiflorin C (7). Key steps in our strategy are the intramolecular cyclopropanation of diazoketone 19 and the regioselective cleavage of the cyclopropane ring.

Structure−Activity Relationship of in Vitro Antiviral and Cytotoxic Activity of Semisynthetic Analogues of Scopadulane Diterpenes

“…In this study we have evaluated the in vitro antiviral and cytotoxic activity of 14 semisynthetic compounds derived principally from the natural diterpenoids TA ( 4 ), TB ( 5 ), and TC ( 6 ) and their precursors. All of the following compounds were synthesized as single isomers from the chiral starting material (+) - podocarp-8(14)-en-13-one: methyl thyrsiflorin A ( 4a , MTA), methyl thyrsiflorin B acetate ( 5a , MTBA), thyrsiflorin C ( 6 , TC), thyrsiflorin C diacetate ( 6a ), 13-scopadulanone ( 7 ), 13α-scopadulanol ( 8 ), 7β-hydroxy-13-scopadulanone ( 9 ), 7β-acetoxy-13β-scopadulanol ( 10 ), 8(14)-scopadulen-13-one ( 11 ), 8(14)-scopadulen-13,15-dione ( 12 ), 7α-hydroxy-8(14)-scopadulen-13-one ( 13 ), cyclopropane intermediate ( 14 ), 7α-hydroxy-8α-scopadulan-13-one ( 15 ), and the rearranged scopadulane-type diterpene ketone ( 16 ).

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“…Compounds. The diterpenoids tested were obtained following the procedure described by us . Stock solutions (7 mg/mL) of these compounds for testing in vitro were prepared in dimethyl sulfoxide and stored at 4 °C.…”

Maleopimaric anhydride ethyl ester

“…Rosin, a versatile natural resin, possesses a rare combination of many desirable properties and has consequently found innumerable industrial uses in a modified form or in conjunction with other natural or synthetic resins (McCoy, 2000). Abietic acid is the major component of colophony (rosin) and is used as a chiral staring material and a useful synthetic intermediate (Arno et al, 2000). Numerous commonly used products can be made from abietic acid, such as paper sizing, printing inks, adhesives, glues, technical resins, synthetic rubber, cosmetics and dental materials (Burge, 1981;Downs et al, 1999).…”

Synthesis of bodinieric acids A and B, both C-18 and C-19-functionalized abietane diterpenoids: DFT study of the key aldol reaction

“…1), as we had worked in the eld 20 years ago. 5 We became interested in developing a scalable synthetic route towards those acids for further study, including the control of the stereoselectivity at the quaternary stereocenter at C-4. Herein, we describe the rst synthesis of bodinieric acids A (3) and B (4) through a key aldol reaction of which we give further insight based on deuterium exchange experiments and DFT computational studies.…”