An easy route to pentacyclic terpenylquinones

Diterpenoids of terrestrial origin

“…38 The availability of a number of bicyclic diterpenes on a reasonable scale has continued to make them convenient starting materials for partial synthesis. 39 Thus terpenylquinones have been synthesized from methyl communate, 40 nidorellol has been converted to ent-ambrox, 41 and ent-halimic acid has formed the starting material for sesquiterpenoid-indole alkaloid synthesis. 42 A number of imbricatolic acid analogues have been prepared in the context of their action on glucose uptake.…”

Bioactive Prenyl- and Terpenyl-Quinones/Hydroquinones of Marine Origin †

“…In addition, the change of the cycloaddition solvent from ethyl ether to dichloromethane, led to the corresponding 1,4-AQ derivatives as the result of the cycloalkylation of the naphthalene core by the prenyl chain. This cyclization was due to the presence of acid traces in the reaction, as shown by several mechanistic studies performed by us [ 171 , 172 ].…”

New Antineoplastic Naphthohydroquinones Attached to Labdane and Rearranged Diterpene Skeletons

“…The starting DTHQs 1 and 2 were prepared through a Diels-Alder cycloaddition between myrceocommunic acid or methyl myrceocommunate and p -benzoquinone ( Scheme 1 ), following the procedure previously described by us [ 11 , 12 ]. Isomerization of the Δ 8(17) double bond, in both 1 and 2 to the more stable endocyclic and tetrasubstituted Δ 8 double bond, was achieved by treatment with aq 57% HI at 80 °C to yield the DTHQs 3 and 4 [ 13 ].…”

“…We have prepared a large number of derivatives with variations in sizes and functionalities of both the quinone and the terpenoid moieties. Very interesting antineoplastic compounds were obtained from β-myrcene [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ] and myrceocommunic acid [ 11 , 12 , 13 , 14 ], being the DTQs/DTHQs slightly more potent than the MTQs/MTHQs. About the quinone size, 1,4-naphthoquinone (NQ) and 1,4-anthracenequinone (AQ) analogues were more potent than the corresponding benzoquinones (BQs) and 9,10-AQs, the common moiety in clinically used anticancer drugs, without significant differences between the quinone functions and the corresponding acetylated hydroquinones.…”