Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• (−)-α-bisabolol. The optimized synthetic route includes a new purification method for isolating (−)-7-amino-7,8-dihydrobisabolene in enantiomerically pure form via recrystallization of its benzamide derivative. The key intramolecular aza-Prins reaction forms the characteristic 3-azabicyclo[3.3.1]nonane

• acids. Keywords: alkaloid; amino acid; aza-Prins reaction; cascade reaction; natural product; Introduction Marine sponges produce a large number of structurally diverse natural products, including many that exhibit biological activity [1][2][3]. In 2019, Tsukamoto and co-workers isolated the

• configuration was not rigorously established, we have assigned it as the (E)-isomer, as is commonly observed in aldimine formation. The stage was now set for the key intramolecular aza-Prins reaction that would form the bicyclic structures of the halichonic acids (Scheme 2). When a solution of imine 7 in

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• Jie Zheng Shuyu Meng Quanrui Wang Department of Chemistry, Fudan University, 2005 Songhu Road, Shanghai 200438, P. R. China 10.3762/bjoc.17.104 Abstract The treatment of 2-(2-vinylphenyl)acetaldehydes or 3-(2-vinylphenyl)propanals with BF3·Et2O results in an intramolecular Prins reaction

• alkynyl-Prins cyclization, Friedel–Crafts alkenylation, and dehydration/aromatization reaction between 1-aryl-3-hexyne-2,6-diol derivatives and aldehydes, that led to the formation of 1,4-dihydro-2H-benzo[f]isochromenes [16]. The Prins reaction-induced cyclization, inter alia, became a versatile tool for

• (Table 1). Thus, the portion-wise addition of AlCl3 (1.1 equiv) to a stirred mixture of 13a (1.0 equiv) and veratrole (1.05 equiv) in CH2Cl2 at 0 °C resulted in the intramolecular Prins reaction to generate a benzyl carbenium ion that concurrently underwent Friedel–Crafts reaction with veratrole, leading

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

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• important building blocks and ubiquitous scaffolds in many natural products and active pharmaceutical ingredients (API). Among various established methods, the Prins reaction has emerged as a powerful technique in the stereoselective synthesis of the tetrahydropyran skeleton with various substituents, and

• metathesis (RCM) [16], halo etherification [17], reductive etherification [18][19], and metal-mediated cyclization [20][21], etc. are the most frequent strategies utilized for THP ring construction (Scheme 1). Amongst all, the Prins reaction has proven as a powerful technique in the stereoselective synthesis

• the synthesis of diol by the condensation of styrene and paraformaldehyde in the presence of a Brønsted acid [23][24]. The major breakthrough for this reaction was reported by Hanschke in 1955, when the THP ring was selectively constructed through a Prins reaction involving 3-butene-1-ol and a variety

A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

• Oksana S. Mikhalchenko,
• Dina V. Korchagina,
• Konstantin P. Volcho and
• Nariman F. Salakhutdinov

Beilstein J. Org. Chem. 2016, 12, 648–653, doi:10.3762/bjoc.12.64

• -fluorohexahydro-2H-chromenes under the developed conditions, the reaction occurs with inversion of configuration. Keywords: chirality; fluorine; halo-Prins reaction; isopulegol; monoterpene; Introduction Recently, we have found that a reaction between para-mentha-6,8-dien-2,3-diol (1) and aromatic aldehydes in

• between monoterpenoid 1 and aromatic aldehydes in the presence of K10 montmorillonite clay. The Prins reaction between homoallylic alcohols and aldehydes. Reaction of compound 1 with aldehyde 6f. A possible mechanism of the compound 2 and 8 formation. Reaction of isopulegol (4) with aldehyde 6a in the

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• single diastereomer) which may be due to the stabilized carbenium ion formed at the benzylic position. This rearrangement presents a relatively rare example of an intramolecular aldol-like reaction of an enol ether with an activated acetal (which may also be regarded as a special case of a Prins reaction

A new intermediate in the Prins reaction

• Shinichi Yamabe,
• Takeshi Fukuda and
• Shoko Yamazaki

Beilstein J. Org. Chem. 2013, 9, 476–485, doi:10.3762/bjoc.9.51

• . Dynamical calculations of a classical trajectory using the atom-centered density matrix propagation molecular dynamics model on the four TSs were carried out, and results of IRC calculations were confirmed by them. Keywords: DFT calculations; hemiacetal intermediate; hydrogen bond; Prins reaction

• ; transition state; Introduction The Prins reaction is the acid-catalyzed addition of aldehydes to alkenes and gives different products depending on the reaction conditions. The first work on the condensation of alkenes with aldehydes was made by Kriewitz in 1899 [1]. He found that unsaturated alcohols were

• was used, and water or glacial acetic acid was the solvent. A general Prins reaction is shown in Scheme 1. A typical Prins reaction is exhibited in Scheme 2 [4]. Here, the six-membered ring compound, 4,4-dimethyl-1,3-dioxane, is the major product along with 3-methyl-1,3-butane-diol. The 1,3-dioxane is

Prins fluorination cyclisations: Preparation of 4-fluoro-pyran and -piperidine heterocycles

• Guillaume G. Launay,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2010, 6, No. 41, doi:10.3762/bjoc.6.41

• Guillaume G. Launay Alexandra M. Z. Slawin David O'Hagan School of Chemistry and Centre for Biomolecular Sciences, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, United Kingdom 10.3762/bjoc.6.41 Abstract The Prins reaction was investigated using BF3·OEt2 as a Lewis acid. It

• Prins reaction is a well established strategy for the synthesis of pyrans [5][6][7]. This cyclisation reaction, which occurs between a homoallylic alcohol and an aldehyde, is generally promoted by a Lewis acid. When BF3·OEt2 is used as the Lewis acid, then fluoride ion from the reagent can become

• incorporated into the product generating a C–F bond and a new stereogenic centre. Liberation of fluoride ion from BF3·OEt2 has, for example, been observed in epoxide ring opening reactions [8][9]. This was first recognised in a Prins reaction as an unexpected side reaction by Al-Mutairi et al. [10][11] and was