Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

•  18A). The reaction worked exclusively for reactive alkenes such as 1,1-disubstituted or trisubstituted alkenes. No conversion was observed for terminal alkenes and 1,2-substituted alkenes. When exposing citronellol (122) to the reaction conditions, the alcohol was rapidly converted to the acetate and

• regioisomers 41 and 68. The formation thereof was previously discussed in Scheme 10. Reactions with polar substrates such as 6-methylhept-5-en-2-one resulted in homogenous reaction conditions and did not require vigorous stirring (product 128). As previously observed by Paquin and co-workers citronellol gave

• activated alkenes [86]. Subjecting citronellol (122) to the optimized reaction conditions resulted in the formation of chloride 133 with a yield of 62% (Scheme 25). It is worth noting that the iron-catalyzed procedure tolerates free alcohols, a distinction from Carreira's protocol [80]. In 2014, the Thomas

Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)

• Tania Xavier,
• Sylvie Condon,
• Christophe Pichon,
• Erwan Le Gall and
• Marc Presset

Beilstein J. Org. Chem. 2021, 17, 2085–2094, doi:10.3762/bjoc.17.135

• such as citronellol (4ja, 58%) and (−)-ethyl lactate (4ka, 32%) could also be employed for the direct preparation of elaborated reagents. Conclusion We have prepared more than 30 SMAHOs including numerous new compounds using different strategies, thus adding a consequent input to the knowledge of these

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• an ene reaction of β-citronellol and Diels–Alder reactions of α-terpinene and (5-methylfuran-2-yl)methanol [46] as well as the synthesis of cyclopent-2-enones from furans [47] and the synthesis of diverse γ-lactam scaffolds [48]. Conversions larger than 90% were achieved for all reactions [46][47][48

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• citronellol derivative via a phosphodiester bridge. Moreover, a novel phosphoramidite chemistry-based method offers a straightforward approach for the non-enzymatic incorporation of the saccharide moiety in an anomerically pure form. Keywords: carbohydrates; citronellol; phosphoramidite; photoclickable

• -mannose (the α-anomer also shows biological activity, but to a lesser extent) [13][14][15], a short-chain (citronellol) mimic of dolichol [1][2][13], and a functional tag. The latter may either be a chemically reactive group (in MPC-1) or a fluorescent reporter group (in MPC-2). MPC-1 bears a benzophenone

• (work in progress). The possibility to use both probes, MPC-1 and MPC-3, independently may help to reduce false-positive scramblase candidates. Results and Discussion The synthesis of the target compounds MPC-1 and MPC-2 started from commercially available (S)-citronellol (Cit), 4,4

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

A method to determine the correct photocatalyst concentration for photooxidation reactions conducted in continuous flow reactors

• Clemens R. Horn and
• Sylvain Gremetz

Beilstein J. Org. Chem. 2020, 16, 871–879, doi:10.3762/bjoc.16.78

• photocatalysts for the oxidation of citronellol (Scheme 1), using the conditions described by Lévesque and Seeberger [23]. The reaction conditions used for the experiments shown in Scheme 1 are detailed in Figure 2 below, and the best results are highlighted in grey. The conversions of the photooxidation

• [38], and 419 nm in toluene [35]). Reactions using calculated photocatalyst concentrations The concentrations calculated for the catalyst were tested using the oxidation of alpha-terpinene (Scheme 2) and the oxidation of citronellol (Scheme 1). All reactions were conducted with 2 equiv of oxygen at 8

• used in conjunction with the maximum amount of light. As such, the question concerning the effect obtained upon variation of the light power arose. The answer to this can be found in Figure 11: rather large changes in the conversion of citronellol were observed as a function of the light power, and a

Synthetic terpenoids in the world of fragrances: Iso E Super^® is the showcase

• Alexey Stepanyuk and
• Andreas Kirschning

Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252

• , a composition of coumarin, oak moss, geranium and bergamot, commercially launched by Houbigant [4]. The major constituents of geranium oil include myrcene (1), menthone (2), α-pinene (3), geraniol (4a), geranyl acetate (4b), geranyl butyrate (4c), citronellol (5), limonene (6) and linalool (9a). As

• monoterpene ether 1,8-cineole (14) and camphene (21) can be isolated from the Siberian fir needle oil. Cymbopogon oils provide among other components borneol (16b), geranyl acetate (4b) and citronellol (5). Besides limonene (6), (−)-carvone (17) is one of the main constituents in caraway oil and dill seed oil

An efficient synthesis of the guaiane sesquiterpene (−)-isoguaiene by domino metathesis

• Yuzhou Wang,
• Ahmed F. Darweesh,
• Patrick Zimdars and
• Peter Metz

Beilstein J. Org. Chem. 2019, 15, 858–862, doi:10.3762/bjoc.15.83

• furnish 25 and subsequent acetal hydrolysis provided the known aldehyde 26 [25] in very good overall yield. In our hands, the "demethanation" of (S)-citronellol to produce the primary alcohol corresponding to aldehyde 26 according to the protocol of Abidi (NaNO2, aqueous AcOH) [26] as a potential shortcut

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow

• Clémentine Minozzi,
• Jean-Christophe Grenier-Petel,
• Shawn Parisien-Collette and
• Shawn K. Collins

Beilstein J. Org. Chem. 2018, 14, 2730–2736, doi:10.3762/bjoc.14.251

• transformed to the corresponding bromide 2 in 99% yield, respectively (Table 1, entry 1). The corresponding bromide of citronellol (4) was also formed in high yield (91%, Table 1, entry 2). A long chain methyl ester 5 was also tolerated under the reaction conditions (98% of the bromide, Table 1, entry 3). The

• % yield. With optimized flow conditions in hand for the formation of bromides in continuous flow, five different alcohols were converted to their corresponding halides (Table 3). The benzyl-protected alcohol 1 could be transformed to the bromide in 83% yield (Table 3, entry 1), as was citronellol (4, 83

Diels–Alder reactions of myrcene using intensified continuous-flow reactors

• Christian H. Hornung,
• Miguel Á. Álvarez-Diéguez,
• Thomas M. Kohl and
• John Tsanaktsidis

Beilstein J. Org. Chem. 2017, 13, 120–126, doi:10.3762/bjoc.13.15

• fragrances are based on myrcene, such as geraniol, nerol, linalool, menthol, citral, citronellol or citronellal [3]. The terminal diene moiety present in myrcene allows for a reaction with a suitable dienophile following the Diels–Alder reaction mechanism. Dahill et al. describe the synthesis of the Diels

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• photooxidations of citronellol [35][40][41][42], indanes [43], monoterpenes [36], furans [42], furfurals [44], thiols [37] and amines [45] as well as the syntheses of ascaridol [46] and artemisinin [47]. Related microreactor setups were applied to biphasic gas/liquid mixtures in the photochlorination of

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• butenolide 140 from (R)-citronellol (139) in an 11-step sequence. Next, the two stereocenters at C2 and C3 position were installed by stereoselective conjugate addition of enantiopure α-allylphosphonamide 141 to butenolide 140. After cleavage of the chiral auxiliary by ozonolysis, aldehyde 142 was protected

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• stereocenters would originate from lactone 82, which in turn is the product of a conjugate addition of chiral allyl phosphonamide reagent 28c to butenolide 83 prepared from (R)-citronellol. The correct installation of the stereocenters of 82 was crucial to the success of the synthesis, as they would form a

• template for the stereocontrolled incorporation of the remaining stereocenters. The construction of butenolide 83 started from (R)-citronellol (84), which could in principle, deliver the entire alkenyl side chain of acetoxycrenulide (10) (Scheme 11). However, the double bond needed to be transformed into a

The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow

• Kimberley A. Roper,
• Malcolm B. Berry and
• Steven V. Ley

Beilstein J. Org. Chem. 2013, 9, 1781–1790, doi:10.3762/bjoc.9.207

• transformation, giving the bromide products in high yield and high purity following removal of the dichloromethane solvent (Table 3). Citronellol (Table 3, entry 1) and an indole derived alcohol (Table 3, entry 2), could be transformed in a facile manner using a single pass of the alcohol through the monolith at

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• one common issue with moving to microflow photochemistry: although yields may increase, productivity can be significantly lower. A glass-loop microreactor was employed in the sensitised oxygenation of (−)-β-citronellol (24) shown in Scheme 9, an important reaction for the synthesis of the fragrance

• with that of alternatives; despite the reported high photon efficiency, an LCE comparison [35] of six methods for the conversion of β-citronellol into rose oxide showed the above method to be less competitive, mainly due to the long irradiation times causing high consumption of electrical power. It

• . However, not all dual channel microreactors need suffer such low productivity; the oxidation of β-citronellol (24) has been performed in the dual channel reactor designed by Kim et al. and gave a daily output of 45.5 mmol (1.9 mmol/h) by using methylene blue as the sensitiser and a 16 W LED light source

Improved syntheses of high hole mobility phthalocyanines: A case of steric assistance in the cyclo-oligomerisation of phthalonitriles

• Daniel J. Tate,
• Rémi Anémian,
• Richard J. Bushby,
• Suwat Nanan,
• Stuart L. Warriner and
• and Benjamin J. Whitaker

Beilstein J. Org. Chem. 2012, 8, 120–128, doi:10.3762/bjoc.8.14

• [16], and this stimulated our efforts to produce further examples [17]. As part of that work we investigated cases in which the α-substituents were branched-chain types. Since we did not want to produce mixtures of diasterioisomers, we used either citronellol-based chains (enantiomerically pure

Triple-channel microreactor for biphasic gas–liquid reactions: Photosensitized oxygenations

• Ram Awatar Maurya,
• Chan Pil Park and
• Dong-Pyo Kim

Beilstein J. Org. Chem. 2011, 7, 1158–1163, doi:10.3762/bjoc.7.134

• oxygenations of α-terpinene, citronellol, and allyl alcohols. Keywords: gas–liquid reaction; microreactor; photosensitization; singlet oxygen; Introduction Microreactors have recently attracted much interest among the scientific community for performing laboratory operations on small scales [1][2][3][4][5][6

• prevent diffusion of solvents from the middle channel to the outer channels. Thus, only oxygen diffuses into the solution and not the opposite way around. The efficiency of the triple-channel microreactor was studied by carrying out photosensitized oxygenation of citronellol, allyl alcohols, and α

• -terpinene. Photosensitized oxygenation of (−)-citronellol The photosensitized oxygenation of citronellol is an industrially important synthetic transformation [47] as it is used for bulk production of a fragrance, rose oxide (Scheme 1). The reaction was performed with methylene blue as a sensitizer in