Abstract:Tour 45, 11, quai Saint-Bernard 75-Paris 5eme) Szcmmary From the ketol (2), previously synthesised from (-)-dihydrocarvone, (+)-daucene, (+)-carotol, and (-)daucol have been prepared.
“…Daucene ( 233 ) is a member of the carotane-type sesquiterpenes and has an unusual hydroazulene skeleton. The daucane (carotane) sesquiterpenes all share a bicyclo[5.3.0]decane core with diverse functionality and varied degrees of oxidation (Figure ) and have been shown to exhibit diverse biological activities. − During the years, several total syntheses of daucene ( 233 ) have been reported. − Seto and co-workers employed a highly regioselective intramolecular [2 + 2] photocycloaddition followed by a retro-aldol reaction to access a variety of carotane-type terpenes, including (±)-daucene . Irradiation of enone 239 resulted in efficient and regioselective photocyclization to afford photoproduct 240 in 88% yield (Scheme ).…”
The use of photochemical transformations
is a powerful strategy
that allows for the formation of a high degree of molecular complexity
from relatively simple building blocks in a single step. A central
feature of all light-promoted transformations is the involvement of
electronically excited states, generated upon absorption of photons.
This produces transient reactive intermediates and significantly alters
the reactivity of a chemical compound. The input of energy provided
by light thus offers a means to produce strained and unique target
compounds that cannot be assembled using thermal protocols. This review
aims at highlighting photochemical transformations as a tool for rapidly
accessing structurally and stereochemically diverse scaffolds. Synthetic
designs based on photochemical transformations have the potential
to afford complex polycyclic carbon skeletons with impressive efficiency,
which are of high value in total synthesis.
“…Daucene ( 233 ) is a member of the carotane-type sesquiterpenes and has an unusual hydroazulene skeleton. The daucane (carotane) sesquiterpenes all share a bicyclo[5.3.0]decane core with diverse functionality and varied degrees of oxidation (Figure ) and have been shown to exhibit diverse biological activities. − During the years, several total syntheses of daucene ( 233 ) have been reported. − Seto and co-workers employed a highly regioselective intramolecular [2 + 2] photocycloaddition followed by a retro-aldol reaction to access a variety of carotane-type terpenes, including (±)-daucene . Irradiation of enone 239 resulted in efficient and regioselective photocyclization to afford photoproduct 240 in 88% yield (Scheme ).…”
The use of photochemical transformations
is a powerful strategy
that allows for the formation of a high degree of molecular complexity
from relatively simple building blocks in a single step. A central
feature of all light-promoted transformations is the involvement of
electronically excited states, generated upon absorption of photons.
This produces transient reactive intermediates and significantly alters
the reactivity of a chemical compound. The input of energy provided
by light thus offers a means to produce strained and unique target
compounds that cannot be assembled using thermal protocols. This review
aims at highlighting photochemical transformations as a tool for rapidly
accessing structurally and stereochemically diverse scaffolds. Synthetic
designs based on photochemical transformations have the potential
to afford complex polycyclic carbon skeletons with impressive efficiency,
which are of high value in total synthesis.
“…It was assigned an absolute configuration enantiomeric to that indicated in 7, based on its co-occurrence with ( + )-a-cedrene, ( + )-prezizaene and ( + )-zizaene. We visualized by analogy to the co-formation of daucene (6) and acoradiene 7 from 5. as described above, a stereospecific conversion of carotol (1) of known absolute configuration (14)(15)(16)(17)(18) into acoradiene 7, thus unequivocally establishing the absolute configuration of the new acoradiene.…”
“…synthon include the use of carvomenthone in the synthesis of copacamphor and copacamphene, 56 caran-2-one in the synthesis of cubebol and the cubabenes 57 and (-)-carvone in the synthesis of (+)-daucene and (+)-carotol. 58 Carvone has been used as α chiral starting material for the synthesis of eudesmanes and dihydroagarofurans 59 as well as for more complex terpenoids and steroids such as the sesquiterpenoid perihysin E. 60 The cyclisation of carvone epoxide 61 by Ti(III) gave 61 functionalised pinenes such as 62 (Scheme 16). The cleavage of these has afforded routes to chiral cyclohexenones (e.g.…”
The preparation of some chiral cyclic synthetic intermediates from car-3-ene, linalool, limonene, α-pinene and camphor, is reviewed. Some applications of these intermediates are described.
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