Matteson Reaction under Flow Conditions: Iterative Homologations of Terpenes

Kuhwald, Conrad; Kirschning, Andreas

doi:10.1021/acs.orglett.1c01222

Cited by 21 publications

(11 citation statements)

References 44 publications

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“…Some have intensive and highly pleasant aroma properties. For instance, the derivatives of ionone Iso E Super Plus ® (CAS 140194-26-9) and (-)-georgywood ® (CAS 828933-31-9) have odor thresholds of only few pg L −1 and are widely used in the cosmetics industry [29,30]. According to their odor properties, the novel geraniol and linalool derivatives could also be interesting flavoring agents, especially considering the fact that linalool and geraniol are two of the most often used flavor compounds in cosmetics, deodorants, and showering agents [31,32].…”

Section: Discussionmentioning

confidence: 99%

Odor Characteristics of Novel Non-Canonical Terpenes

et al. 2022

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Several non-canonical, methylated terpenes have been described as products of genetically modified Escherichia coli recently, and the aroma properties of 28 odor-active methylated derivatives of prenol, isoprenol, bornane, camphene, carene, citronellol, fenchol, geraniol, limonene, linalool, terpineol, and farnesol were characterized for the first time in the current study. Twelve methylated monoterpenes exhibited a particularly intense and pleasant odor and were therefore chosen for the determination of their respective odor thresholds (OTs) in comparison to their non-methylated equivalents. In addition to the determination of OTs based on the literature value for the internal standard, (2E)-decenal, the threshold values of the compounds with individually determined OTs of the participants were calculated. This enabled a more precise identification of the OTs. Among the non-canonical terpenes, the lowest OTs in the air were found for 2-methyllinalool (flowery, 1.8 ng L−1), 2-methyl-α-fenchol (moldy, 3.6 ng L−1), 2-methylgeraniol (flowery, 5.4 ng L−1), 2-methylcitronellol (citrus-like, 7.2 ng L−1), and 4-methylgeraniol (citrus-like, 16 ng L−1). The derivatives of geraniol, linalool, and citronellol showed very pleasant odor impressions, which could make them interesting for use as flavoring agents in the flavor and fragrance industry.

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Section: Discussionmentioning

confidence: 99%

Odor Characteristics of Novel Non-Canonical Terpenes

et al. 2022

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“…Very recently, Kirschning and co-workers presented a general method for the Matteson reaction in flow, allowing iterative homologation of various terpene boronate esters 17 , which are subsequently oxidized to the corresponding alcohols 20 ( Scheme 5 ) [ 35 ]. In the first step, a solution of terpenyl pinacol boronates 17 and bromochloromethane in tetrahydrofuran is mixed with n -butyllithium in n -hexane at −40 °C.…”

Section: Reviewmentioning

confidence: 99%

“…Alcohol 22 has a citrus and menthol note, while its homolog 23 shows a turpentine-like, woody scent. In contrast, alcohol 24 , which is a homolog of geraniol, has a strong fruity, melon-like odor profile [ 35 ].…”

Section: Reviewmentioning

confidence: 99%

Synthesis of odorants in flow and their applications in perfumery

Kleoff

Kiler²,

Heretsch

2022

Beilstein J. Org. Chem.

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Continuous flow technology is a key technology for sustainable manufacturing with numerous applications for the synthesis of fine chemicals. In recent years, the preparation of odorants utilizing the advantages of flow reactors received growing attention. In this review, we give an overview of selected methods for the synthesis of odorants in flow, including heterogeneously catalyzed reactions, gas reactions, and photochemical C–H functionalization processes. After a brief introduction on types of odorants, the presented odorant syntheses are ordered according to the main odor families “fruity”, “green”, “marine”, “floral”, “spicy”, “woody”, “ambery”, and “musky” and their use and importance for perfumery is briefly discussed.

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“…In Figure C, the average results obtained for the T-mixer (Bola) are compared to the other passive mixers. It is noteworthy to mention that comparison between mixing times should be made only between the same solvent and flow rate ratio, as mixing times typically change, more specifically, diminish with the viscosity and increase with asymmetric flow ratios. , Especially for organometallic reactions, where highly concentrated bases (e.g., butyl lithium or Grignard reagent) are mixed with diluted substrates, ratios in the range of 1:10 are common, which drastically reduces mixing performance. Interestingly, all of the presented mixers led to an improved mixing performance compared to the T-mixer.…”

Section: Introductionmentioning

confidence: 99%

Minimizing Material Consumption in Flow Process Research and Development: A Novel Approach Toward Robust and Controlled Mixing of Reactants

Haber

Ausserwoeger

Lehmann

et al. 2022

Org. Process Res. Dev.

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Scarce availability of chemical starting materials is a crucial challenge in the development of flow chemical processes. This is particularly important for organometallic reactions, which typically require high flow rates and hence high material consumption, to generate sufficiently short mixing and residence times. To address this issue, micromixers that mix efficiently even at small Re numbers and that have a low tendency of clogging are necessary. Here, we propose the usage of microannular gear pumps as active mixers, which allow the reduction of material consumption by >10-fold while achieving fast mixing times for common organometallic reactions. This novel approach is benchmarked against several commercially available mixers with respect to the mixing time at low flow rates, showing that the gear pumps can achieve fast mixing (< 50 ms) even at <1 mL/min. To assess the crucially important factor of time to blockage in a consistent manner, a novel protocol is developed based on the controlled precipitation of lithium salts during the mixing process. This shows that the gear pump is significantly more robust than common mixers as operation can be maintained for over 2 h. Lastly, we highlight that the microannular gear pump approach allows the manipulation of mixing time at equal residence time, by tuning the rotation speed, thus allowing for characterization of the mixing sensitivity of reactions. Taken together, our multiparametric analysis of common mixing approaches highlights that the usage of microannular gear pumps for active mixing of fast organometallic reactions presents a powerful alternative able to address current limitations of organic process development.

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Matteson Reaction under Flow Conditions: Iterative Homologations of Terpenes

Cited by 21 publications

References 44 publications

Odor Characteristics of Novel Non-Canonical Terpenes

Odor Characteristics of Novel Non-Canonical Terpenes

Synthesis of odorants in flow and their applications in perfumery

Minimizing Material Consumption in Flow Process Research and Development: A Novel Approach Toward Robust and Controlled Mixing of Reactants

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