Continuous catalyst-free aromatization of γ-terpinene using air as an oxidant

Asikainen, Martta; Jauhiainen, Olli; Aaltonen, Olli; Harlin, Ali

doi:10.1039/c3gc41224e

Cited by 33 publications

(16 citation statements)

References 25 publications

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“…Thereby, 3,4-dimethylcumene and the two diastereomers of 2-methylcitronellol are downstream metabolites of further conversions of primary C11-terpene synthase products that are formed by spontaneous or enzymatically catalyzed reactions. 3,4-Dimethylcumene is likely the product of a spontaneous oxidation of 2-methyl-γ-terpinene, in analogy to the reported spontaneous oxidation of the corresponding monoterpene γ-terpinene to p-cymene [ 35 , 36 ]. Since no reference substance is available for 2-methyl-γ-terpinene the presence of the probable precursor of 3,4-dimethylcumene could not be proven in this study.…”

Section: Discussionmentioning

confidence: 83%

Heterologous expression of 2-methylisoborneol / 2 methylenebornane biosynthesis genes in Escherichia coli yields novel C11-terpenes

et al. 2018

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The structural diversity of terpenoids is limited by the isoprene rule which states that all primary terpene synthase products derive from methyl-branched building blocks with five carbon atoms. With this study we discover a broad spectrum of novel terpenoids with eleven carbon atoms as byproducts of bacterial 2-methylisoborneol or 2-methylenebornane synthases. Both enzymes use 2-methyl-GPP as substrate, which is synthesized from GPP by the action of a methyltransferase. We used E. coli strains that heterologously produce different C11-terpene synthases together with the GPP methyltransferase and the mevalonate pathway enzymes. With this de novo approach, 35 different C11-terpenes could be produced. In addition to eleven known compounds, it was possible to detect 24 novel C11-terpenes which have not yet been described as terpene synthase products. Four of them, 3,4-dimethylcumene, 2-methylborneol and the two diastereomers of 2-methylcitronellol could be identified. Furthermore, we showed that an E. coli strain expressing the GPP-methyltransferase can produce the C16-terpene 6-methylfarnesol which indicates the condensation of 2-methyl-GPP and IPP to 6-methyl-FPP by the E. coli FPP-synthase. Our study demonstrates the broad range of unusual terpenes accessible by expression of GPP-methyltransferases and C11-terpene synthases in E. coli and provides an extended mechanism for C11-terpene synthases.

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Section: Discussionmentioning

confidence: 83%

Heterologous expression of 2-methylisoborneol / 2 methylenebornane biosynthesis genes in Escherichia coli yields novel C11-terpenes

et al. 2018

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“…The rate of reaction depends upon the vapor/liquid phase equilibrium and the amount of oxygen in the vapor phase (285).…”

Section: Scheme 59 Oxidations Of 2- 3- or 4-picolinementioning

confidence: 99%

Managing Hazardous Reactions and Compounds in Process Chemistry

Ager¹

2014

ACS Symposium Series

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“…73 Under carefully controlled conditions the oxygen in the air can act as a hydrogen acceptor in the conversion of γ-terpinene to p-cymene. 74 Various oxidants have been used for the conversion of γ-terpinene to p-cymene including potassium permanganate on alumina in a ball mill, 75 and selenium dioxide activated with trimethylsilylpolyphosphate with which 100% conversions of the terpinenes to cymene were reported. 76 Amongst the sesquiterpenoid dehydrogenation products, guaiazulene 22 is attracting considerable interest.…”

Section: Some Current Studies On Terpenoid Aromatisation Productsmentioning

confidence: 99%