Total synthesis of humulene

Artificially mimicking the cyclase phase of terpene biosynthesis inspires the invention of new methodologies, since working with carbogenic frameworks containing minimal functionality limits the chemist’s toolbox of synthetic strategies. For example, the construction of terpene skeletons from five-carbon building blocks would be an exciting pathway to mimic in the laboratory. Nature oligomerizes, cyclizes, and then oxidizes γ,γ-dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) to all of the known terpenes. Starting from isoprene, the goal of this work was to mimic Nature’s approach for rapidly building molecular complexity. In principle, the controlled oligomerization of isoprene would drastically simplify the synthesis of terpenes used in the medicine, perfumery, flavor, and materials industries. This article delineates our extensive efforts to cooligomerize isoprene or butadiene with alkynes in a controlled fashion by zero-valent nickel catalysis building off the classic studies by Günther Wilke and coworkers.

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“…73 As an alternative, the possibility of delaying the olefin isomerization to a subsequent transformation was considered. 74,75 …”

Section: Planning and Historical Contextmentioning

confidence: 99%

An Approach to Mimicking the Sesquiterpene Cyclase Phase by Nickel-Promoted Diene/Alkyne Cooligomerization

2012

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“…13 C-NMR Spectra: on the instruments operating at 67.9 or 100.5 MHz with CDCl 3 as the solvent and internal standard (d 77.05).…”

Section: Experimental Partmentioning

confidence: 99%

“…The sulfone 12 for the modified Julia coupling reaction was prepared from dimethyl 3-methylglutaconate 5 ((E)/(Z) 2 :1; cf. Scheme 2) [13]. The reduction of 5 with LiAlH 4 , followed by silica-gel column chromatography, gave diol 6 in 37% yield.…”

mentioning

confidence: 99%

Membrane Properties of Branched Polyprenyl Phosphates, Postulated as Primitive Membrane Constituents

Gotoh

Miki

Nagano

et al. 2006

Chemistry & Biodiversity

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We have postulated earlier that the highly branched isoprenoid alkanes, which are distributed widely in many sediments, may have been derived from the corresponding branched polyprenyl phosphates, potentially present in biomembranes in primitive organisms. These polyprenyl-branched polyprenyl phosphates might be derived by a simple alkylation from non-substituted polyprenyl phosphates, which we postulate to be the precursors of all membrane terpenoids. We have now synthesized a series of 6-(poly)prenyl-substituted polyprenyl phosphates and studied the formation of vesicles from these phosphates, as a function of the substituted-chain length, the position of the double bond, and pH. Nine of the branched polyprenyl phosphates containing 20-30 C-atoms do form vesicles at a 'physiological' pH; the lipophilicity/hydrophilicity ratio is as expected an important factor. We have also studied the water permeability through membranes of these branched polyprenyl phosphate vesicles by our stopped-flow/light-scattering method. These highly branched polyprenyl phosphates can more effectively reduce the water permeability than non-substituted polyprenyl phosphates: the vesicles formed by the former are more stable against mechanical stress. This reinforces our hypothesis about the origin of the sedimentary polyprenyl-substituted polyprene hydrocarbons.

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“…5-52. Combining the photolytic C-o scission of benzylic or allylic C-S bonds with the desulfurization of the resultant thiyl radicals by tervalent phosphorus solvents (a reaction dis covered by Walling), Corey and Block developed a method for desulfuriza tion with concomitant C-C bond formation (Corey and Block, 1969). The homolytic sequence is illustrated for dibenzyl sulfide in Eq.…”

Section: Generalmentioning

confidence: 99%

Sulfur-Containing Radical

1978

Organic Chemistry: A Series of Monographs

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Total synthesis of humulene

Cited by 96 publications

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An Approach to Mimicking the Sesquiterpene Cyclase Phase by Nickel-Promoted Diene/Alkyne Cooligomerization

An Approach to Mimicking the Sesquiterpene Cyclase Phase by Nickel-Promoted Diene/Alkyne Cooligomerization

Membrane Properties of Branched Polyprenyl Phosphates, Postulated as Primitive Membrane Constituents

Sulfur-Containing Radical

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