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

• thermodynamically disfavored trans-2,6-tetrahydropyran 260 was reported by Cha and co-workers based on the coupling of hydroxyethyl-tethered cyclopropanol 258 and aliphatic aldehyde 259 using TiCl4 as a Lewis acid [104][105]. The reaction proceeded through the Prins cyclization (Scheme 61). The reaction proceeded

Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups

• Benjamin Jeffries,
• Zhong Wang,
• Robert I. Troup,
• Anaïs Goupille,
• Jean-Yves Le Questel,
• Charlene Fallan,
• James S. Scott,
• Elisabetta Chiarparin,
• Jérôme Graton and
• Bruno Linclau

Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182

• ., D5→E5 and G10→E5) which interestingly, are of the same magnitude as for the nonfluorinated derivatives (compare D1, G1 to E1, Figure 6). It is worth noting that “cyclisation” to give cyclopropanol derivatives substituted with a fluorinated methyl group (not shown) can also be considered. Marketed

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• α‐carbonyl radicals was likewise reported [50]. On the contrary, the Mn(acac)3 photocatalyzed ring opening of cyclopropanol 6.2 gave an easy access to a β‐carbonyl radical 6.5·, which in turn added onto 2-biphenyl isocyanide 6.1 to give the corresponding 6-β-ketoalkyl phenanthridine 6.3 in a good

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• , followed by a subsequent trapping of the resulting cyclopropylmetal species with an electrophilic source of oxygen (oxenoid) afforded various tetrasubstituted cyclopropanol derivatives in high diastereo- and enantiomeric ratios. Similarly, the enantioselective copper-catalyzed carbomagnesiation/oxidation

• (or amination) sequence on achiral nonfunctionalized cyclopropenes provided the desired cyclopropanol (and cyclopropylamine) derivatives in excellent diastereo- and enantiomeric excesses. Keywords: carbocupration; cyclopropanol; cyclopropene; regioselectivity; stereoselectivity; Introduction The

• cyclopropanol by Cottle [7], the most popular methods for the preparation of cyclopropanols rely on the transformation of enolates [8][9], silyl enol ether [10][11][12], vinyl borane [13][14][15][16][17], Fischer carbene addition [18], addition of nucleophiles to carbonyl groups [19][20][21][22][23][24][25

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• outlined in Scheme 21. Firstly, the sulfate radical anion 97 is generated from persulfate 96 under the action of Ag(I). Next, the radical 97 reacts with cyclopropanol 91 to give the cyclopropoxy radical 98, which undergoes a ring-opening process to produce β-keto radical 99. The radical 100 is formed

• 106. The Togni reagent (105) reacts with CuCl to generate Cu(III) complex 108. Then, the intermediated 109 is generated from the electrophilic attack of copper(III) 108 with cyclopropanol 91. Finally, the desired product 106 is formed through reductive elimination of CuCl in intermediated 109. On the

• carried out with inexpensive reagents and can also be applied to the distal bromination of cycloalkanols. The possible mechanism is outlined in Scheme 28. The cycloalkoxy radical 98 is generated from cyclopropanol 91 under the action of the metastable Ag(II) species, which is formed by the interaction of

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• : Moving away the CF3 group by one carbon atom further from the carbonyl function would provide the corresponding β-trifluoromethyl ketones. For this aim, distally trifluoromethyl ketones were synthesised by the ring-opening of cyclopropanol derivatives by means of per- or polyfluorinated sulfonates

• of an electrophilic pathway (versus SET pathway) was suggested by regioselective trifluoromethylation of a case substrate. Although Cu(II) acetate was used, the authors mentioned that Cu(I) can be formed in situ by reduction with MeOH or the cyclopropanol. Concomitant mechanisms are depicted in

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• with CF3C(O)OH in Et2O/H2O at 0 °C to obtain optically active 1-indanone 230. A very interesting approach for the synthesis of 1-indanones 234 based on the rearrangement of cyclopropanol derivatives 233, has been reported in 2012 by Rosa and Orellana [94]. This reaction was carried out in the presence

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• Eietsu Hasegawa Minami Tateyama Ryosuke Nagumo Eiji Tayama Hajime Iwamoto Department of Chemistry, Faculty of Science, Niigata University, Ikarashi-2 8050, Niigata 950-2181, Japan 10.3762/bjoc.9.156 Abstract Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol

• proposed. Keywords: copper(II) salt; cyclopropanol; electron transfer; free radical; radical ion probe; Introduction Radical ions are key intermediates in electron-transfer (ET) reactions of organic molecules [1][2][3][4][5] and they often undergo fragmentations to yield free radicals and ions [6][7][8

• hexenyl radical cyclization reactions [21], (Figure 1) [22][23][24][25][26][27][28][29][30]. For example, PET reactions of probe I with amines were observed to produce a spirocyclic ketone product while its reduction reaction induced by samarium diiodide (SmI2) gives rise to a cyclopropanol (left in

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• the various approaches to access these ubiquitous scaffolds, the gold(I)-catalyzed ring expansion of cyclopropanols and cyclobutanols is considered one of the most powerful and versatile methods. In 2005, Toste and co-workers reported the treatment of 1-(phenylethynyl)cyclopropanol (11) with tris(4

• remarkable synthetic application of a gold-catalyzed ring expansion of cyclopropanols in enynic substrates [55]. Vinyl cyclopropanol 77 reacts with Ph3PAuBF4 via cyclization, followed by a selective semi-pinacol shift via carbocationic intermediate 78, to give cyclobutanone 79, which is readily transformed

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• believed to involve single-electron oxidation of the cyclopropanol, fragmentation of a transient radical cation, and diastereoselective radical cyclization. In the enantioselective synthesis, this transformation was more efficiently achieved by treatment of enantioenriched 41b with the AgNO3-ammonium