1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• (101), without the need for any protecting groups (Scheme 15b). Our group has also investigated non-cyclic analogs of 5,6-dihydro-1,4-dithiin-2-ylmethanol (90), such as the dimethylthio-substituted allyl alcohol 105 (Scheme 16) [103]. Surprisingly, we have found that these allyl alcohols totally lack

• starting material (viz 107). These observations are more in line with the reactivity observed for normal allyl cations (where oligomerizations to linear dimers are also the main reaction pathways). The discrepancy between the reactivity of allyl alcohols 99 and 105 can perhaps again be related to the

• of dithiin-fused allyl alcohols and similar non-cyclic sulfur-substituted allyl alcohols. Applications of dihydrodithiins in the rapid assembly of polycyclic terpenoid scaffolds [108][109]. Dihydrodithiin-mediated allyl cation and vinyl carbene cycloadditions via a gold(I)-catalyzed 1,2-sulfur

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• reactor; Introduction Catalytic hydrogenation of α,β-enones is a significant transformation in organic synthesis [1]. Hydrogenation of enones can give ketones, allyl alcohols, and saturated alcohols, and the control of the chemoselectivity is important. Therefore, there have been numerous studies on the

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• in a 9:1 ratio. After chromatographic separation, alcohol (−)-77a, isolated in 67% yield and >99% de was subjected to a Claisen rearrangement, leading to aldehyde (−)-78 in 79% yield (96% de determined by 1H NMR). (−)-78 was treated with vinylmagnesium bromide to give a mixture of allyl alcohols

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• co-workers reported a photoinduced oxidation of allyl alcohols to acrylaldehydes at room temperature, catalyzed by diphenyl disulfide derivatives [18]. In the proposed mechanism, disulfide is split by the photoirradiation to form thiyl radicals. Then, the abstraction of the α-hydrogen atom from allyl

• disulfide-catalyzed isomerization of allyl alcohols to carbonyl compounds under high-pressure mercury lamp irradiation (λ > 300 nm) at room temperature. The yield of the reaction reached up to 91% (Scheme 23) [30]. Using the water-soluble dendrimer disulfide, the photoinduced isomerization in water was also

• successful. For the photoinduced oxidation reaction of allyl alcohols, the dendrimer disulfide is a better mediator than diphenyl disulfide, because dendritic substituents are quite effective in inhibiting side reactions initiated by the addition of sulfanyl radicals to the unsaturated bonds. A plausible

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• calculations. Hydrolysis of these species resulted in the formation of phosphoryl-substituted allyl alcohols and 1,3-butadienes. A strong coordination of the oxygen of the P=O group with AlCl3 prevented the formation of cyclic 1,2-oxaphospholium ions and played a crucial role in the different reactivity of

• Supporting Information File 1). On the other hand, hydrolysis of cations C,D, bearing a stable P–N bond, resulted in the formation of allyl alcohols 4. Aqueous work-up of a superacidic solution of cation E4 led to azaphosphepine-5-oxide 5. This substance is insoluble in organic solvents, however, we were

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• mixtures, (arylsulfinyl)allenes give allyl alcohols (ArSO2–CR1=CH–C(OH)R2R3). Plausible reaction mechanisms have been proposed for all studied reactions. Keywords: (arylsulfinyl)allenes; (arylsulfonyl)allenes; butadienes; 1,2-oxathiolium ions; thiochromene 1,1-dioxides; Introduction Allenes are widely

• ]. Indeed, the use of HFIP and a catalytic amount of TfOH (0.1 equiv) followed by hydrolysis allowed to achieve an exclusive formation of allyl alcohols Z-4a,b and E-4c from allenes 2a,b,d, respectively, in high yields (Scheme 4). The most probably, this reaction proceeds through intermediate formation of

• )allenes 1a,b under superelectrophilic activation with TfOH or AlX3 (X = Cl, Br). The corresponding cations Aa,b generated from 1a,b in TfOH were subjected to quenching with various nucleophiles followed by hydrolysis (Scheme 7). In all the cases, allyl alcohols 7a,b were isolated (see X-ray structure of

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• with benzaldehyde, p-nitro-, and p-methoxybenzaldehyde as described recently by Ponomarenko and Röschenthaler et al. [34]. Considering our earlier results [31] on TMSOTf-mediated Claisen-type rearrangements of SF5-acetates of allyl alcohols, we favor the initial formation of (Z)-enolates (ketene

First DMAP-mediated direct conversion of Morita–Baylis–Hillman alcohols into γ-ketoallylphosphonates: Synthesis of γ-aminoallylphosphonates

• Marwa Ayadi,
• Haitham Elleuch,
• Emmanuel Vrancken and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2906–2915, doi:10.3762/bjoc.12.290

• step protocol involves firstly the mesylation of corresponding alcohols and then the conversion of the intermediate mesylates into their halides. Further an Arbuzov reaction of alkyl phosphites with such halides affords the phosphonates. Interestingly, a direct conversion of common allyl alcohols into

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• Tsuji–Trost reaction involving, as substrates, allyl carboxylates [2], carbonates [3], and phosphates [4]. Obviously, the direct nucleophilic allylic substitution of allyl alcohols is a more attractive process especially from an economical and environmental point of view [5], as water, generated by this

• reaction, is a non-toxic byproduct. However, the poor ability of the hydroxy moiety, as a leaving group, has limited the use of the allyl alcohols as substrates. Correlatively, some efforts have been made in this direction by the use of transition metals such as copper [6], nickel [7], ruthenium (I, II) [8

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• these transformations, allylic oxidations are of high interest because the olefinic starting materials are readily available as cheap bulk chemicals and many interesting derivatives such as terpenes are available from renewable sources [3][4][5]. In addition, the resulting allyl alcohols [6][7][8][9][10

• (1). Only one enantiomer of racemic compounds is shown. Oxidation of vitispirane (23) with PSA gave enone 24 and two diastereomeric allyl alcohols 26a and 26b. A putative intermediate is epoxide 25, which upon hydrolysis would give allyl alcohols 26a and 26b. Oxidation of the latter might provide

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

• Jungho Jun,
• Hyu-Suk Yeom,
• Jun-Hyun An and
• Seunghoon Shin

Beilstein J. Org. Chem. 2013, 9, 1724–1729, doi:10.3762/bjoc.9.198

• of an excess component. Expanding upon the intermolecular coupling reactions of readily available alkenes with alkynes would significantly enhance the synthetic utility of gold catalysis and therefore should find fruitful applications. While it has been known for a long time that allyl alcohols

• effective (Table 1, entries 14–18). Finally, SbF6– turned out to be an optimal counter-anion for cationic [Au(PPh3)]+ (Table 1, entries 19–21). A control experiment with AgSbF6 as the only catalyst led to no reaction (Table 1, entry 22). Apparently, unlike allyl alcohols, sterically bulkier allyl ethers do

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

• performing photosensitized oxygenation of α-terpinene, citronellol and allyl alcohols. As a result of the increased illumination as well as the increased gas–liquid contact area per unit volume, the triple-channel microreactor exhibited better performance in the oxygenations of citronellol, allyl alcohols

The allylic chalcogen effect in olefin metathesis

• Yuya A. Lin and
• Benjamin G. Davis

Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140

• tolerance of the catalyst for sulfur; the enhanced reactivity relative to other alkenes was apparently unnoticed. Our results showed that allyl sulfides are not simply tolerated as they can enhance the rate of olefin metathesis in a similar yet more effective way compared to allyl alcohols and ethers. This

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• efficient Friedel–Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel–Crafts conditions as benzyl-, propargyl- and allyl alcohols

• environmentally benign substrates which can be applied today as an approach towards greener processes. Additionally, the first diastereoselective and enantioselective Friedel–Crafts-type alkylations will be highlighted. Keywords: allyl alcohols; arene; asymmetric Friedel–Crafts reaction; benzyl alcohols; Friedel

• in high yields (Scheme 4). Other rare-earth trifluormethanesulfonates such as Nd(OTf)3 Yb(OTf)3 and Sm(OTf)3 showed similar reactivities and the reaction was later also performed in the ionic liquids [BMIM][OTf] and [BMIM][PF6] [6]. Next to benzyl alcohol, allyl alcohols, dibenzylethers as well as

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• allyl alcohols using diphenyldichlorosilane and imidazole as the base and allowing the reaction to proceed to equilibrium, hopefully allowing for the optimum yield of the mixed acetal. The result shows that the desired mixed acetal is the major product of the reaction as expected. However, given the

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid

• Biswajit K. Singh,
• Surendra S. Bisht and
• Rama P. Tripathi

Beilstein J. Org. Chem. 2006, 2, No. 24, doi:10.1186/1860-5397-2-24

• ] These compounds were treated with DBU separately to get the intermediate allyl alcohols 5 and 6 in good yields, and the structures were confirmed by analysis of the spectroscopic data (Supporting Information File 1). The Z geometry of the double bond in these compounds has been established based on