Synthesis of 8-Hydroxygeraniol

Ippoliti, Francesca M.; Barber, Joyann S.; Tang, Yi; Garg, Neil K.

doi:10.1021/acs.joc.8b01544

Cited by 11 publications

(9 citation statements)

References 24 publications

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“…To determine whether the alkene isomerization step was contributing to the low overall yield of the cascade reaction, orcinol was condensed with the preisomerized α,β-unsaturated aldehyde E-19, instead of 14 (Scheme 4). However, this reaction gave the tetracyclic products 4 and 26 in yields very similar to those of the previous cascade reaction with 14.…”

supporting

confidence: 74%

“…The conjugation of the Δ 12 alkene with the C-14 ketone of 12 would perhaps allow a stepwise, intramolecular [2 + 2] cycloaddition to give rubiginosin A (4) under acidic or basic conditions (again with retention of the alkene stereochemistry in the cyclobutane product). Chromene natural products such as 11 could be synthesized via a Knoevenagel condensation between an electron rich phenol (in this case orcinol, 13) and an appropriate α,β-unsaturated aldehyde (14) to give an ortho- quinone methide (o-QM), 11 followed by oxa-6π-electrocyclization. 12 As part of our continuing studies on the cascade reactions of electron-rich chromenes in biomimetic synthesis, 13 we initially planned to combine the "chromenylation" reaction between 13 and 14 with the subsequent alkene isomerization and stepwise [2 + 2] cycloaddition under acid or base catalysis to achieve a short total synthesis of racemic rubiginosin A. Synthesis of α,β-unsaturated aldehyde 14 (Scheme 2) commenced with the preparation of allylic bromide 15 in two known steps: SeO 2 -mediated hydroxylation of geranyl acetate, 14 followed by bromination of the resultant 8hydroxygeraniol.…”

mentioning

confidence: 99%

“…Chromene natural products such as 11 could be synthesized via a Knoevenagel condensation between an electron rich phenol (in this case orcinol, 13) and an appropriate α,β-unsaturated aldehyde (14) to give an ortho- quinone methide (o-QM), 11 followed by oxa-6π-electrocyclization. 12 As part of our continuing studies on the cascade reactions of electron-rich chromenes in biomimetic synthesis, 13 we initially planned to combine the "chromenylation" reaction between 13 and 14 with the subsequent alkene isomerization and stepwise [2 + 2] cycloaddition under acid or base catalysis to achieve a short total synthesis of racemic rubiginosin A. Synthesis of α,β-unsaturated aldehyde 14 (Scheme 2) commenced with the preparation of allylic bromide 15 in two known steps: SeO 2 -mediated hydroxylation of geranyl acetate, 14 followed by bromination of the resultant 8hydroxygeraniol. 15 Substitution of allylic bromide 15 with the alkynylcopper species derived from 2-methyl-3-butyn-2-ol was achieved using conditions originally developed by White and co-workers (stoichiometric CuI and Et 3 N in Et 2 O/ DMF) 16 to give alkynol 16.…”

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confidence: 99%

“…Synthesis of α,β-unsaturated aldehyde 14 (Scheme ) commenced with the preparation of allylic bromide 15 in two known steps: SeO 2 -mediated hydroxylation of geranyl acetate, followed by bromination of the resultant 8-hydroxygeraniol . Substitution of allylic bromide 15 with the alkynylcopper species derived from 2-methyl-3-butyn-2-ol was achieved using conditions originally developed by White and co-workers (stoichiometric CuI and Et 3 N in Et 2 O/DMF) to give alkynol 16 .…”

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Biomimetic Total Synthesis of the Rubiginosin Meroterpenoids

et al. 2020

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Total synthesis of the Rhododendron meroterpenoids rubiginosins A and G, which both contain unusual 6−6−6−4 ring systems, has been achieved using a bioinspired cascade approach. Stepwise synthesis of these natural products, and the related 6−6−5−4 meroterpenoids fastinoid B and rhodonoid B, from naturally occurring chromene precursors is also reported.Rhododendron plants are a rich source of stereochemically complex, polycyclic meroterpenoids. Among the various possible scaffolds, the 6−6−6−4 ring system (Figure 1a) is

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Biomimetic Total Synthesis of the Rubiginosin Meroterpenoids

et al. 2020

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“…Other chemicals in this study were of analytical grade. 8-Hydroxygeraniol was prepared according to the method described by Ippoliti et al 27 8-Hydroxyltetrahydrogeraniol was synthesized as following: FeCl 3 •6H 2 O (10 mg) and 8-hydroxygeraniol (100 mg) were mixed in ethanol (5 mL). Then, aqueous hydrazine (300 μL) was immediately added in the mixture.…”

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confidence: 99%

Aspergillus oryzae Biosynthetic Platform for de Novo Iridoid Production

Duan

Liu

et al. 2021

J. Agric. Food Chem.

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The iridoids and their derivatives monoterpene indole alkaloids (MIAs) are two broad classes of plant-derived natural products with valuable pharmaceutical properties. However, the poor source limited their application. Nepetalactol, a common iridoid scaffold of MIAs, was heterologously produced in Saccharomyces cerevisiae. Although the optimization of nepetalactol production in S. cerevisiae was achieved by metabolic engineering, the inherent metabolic constraints impose a restriction on the production. Herein, we developed a high nepetalactol-producing Aspergillus oryzae platform strain. First, the co-expression of 5 nepetalactol biosynthetic genes, in a high isopentenyl pyrophosphate (IPP)-producing strain A. oryzae AK2, succeeded in the biosynthesis of nepetalactol. Second, the improvement of the IPP supply and the suppression of the byproduct citronellol formation were simultaneously achieved. Finally, the highest titer of nepetalactol of 7.2 mg/L was obtained with the engineered strain, after the optimization of the carbon source. To the best of our knowledge, this is the highest reported titer of nepetalactol in microbial cells. The developed A. oryzae strain represents an attractive biosynthetic platform host for the de novo production of iridoids and MIAs.

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Synthesis of 8‐Hydroxygeraniol

Ippoliti¹,

Barber²,

Garg³

et al. 2020

Organic Syntheses

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This article describes the procedure for synthesis of 8‐hydroxygeraniol, which is a key biosynthetic precursor to all monoterpene indole alkaloids (MIAs). It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards. The notorious poison strychnine is just one example of an MIA that arises biosynthetically from strictosidine. Other examples including medicinally important compounds such as the anti‐cancer agent vinblastine, the antimalarial medicine quinine, and ajmalicine, used to treat high blood pressure. Two reports were disclosed in 1970, which involved the use of either levulinaldehyde or dehydrolinalool to prepare 8‐hydroxygeraniol through multistep synthetic sequences.

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Synthesis of 8-Hydroxygeraniol

Cited by 11 publications

References 24 publications

Biomimetic Total Synthesis of the Rubiginosin Meroterpenoids

Biomimetic Total Synthesis of the Rubiginosin Meroterpenoids

Aspergillus oryzae Biosynthetic Platform for de Novo Iridoid Production

Synthesis of 8‐Hydroxygeraniol

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