1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• phenethylamine derivatives (amphetamine, methamphetamine, 2,5-dimethoxy-4-methylamphetamine, mescaline, ephedrine, and norephedrine). The reaction products were separated by thin-layer chromatography and analyzed by elemental analysis, nuclear magnetic resonance, infrared spectroscopy, and mass spectrometry. In

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• debenzylated by the treatment with NaI to generate the corresponding monobenzyl ester 204. The ester 204 was resolved with (−)-ephedrine and then O-benzylated with O-benzyl-N,N'-dicyclohexylurea (205) to give the (R)-1-hydroxy-3-methylbutylphosphonate ((R)-203). The latter was coupled with N-Boc-protected

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• triflate and the chiral additive N-methylephedrine [14] gave the (S)-propargyl alcohol 17 in 72% ee; the chiral purity could be improved to 96% ee by recrystallization. Unfortunately, attempts to catalyze this reaction with Zn(OTf)2/ephedrine were unsuccessful. More recently, Ghosh and co-workers [15] used

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• Electroorganic transformations using chiral supporting electrolytes have not been extensively explored, and the first example of such a reaction was reported by Horner in 1968 [54]. Interestingly, 4.6% ee was achieved in the electroreduction of acetophenone using ephedrine hydrochloride (55a) as chiral

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• )-28. After reductive aziridine ring opening N-Boc-norephedrine ((1R,2S)-29) was formed. The synthesis of (−)-ephedrine ((1R,2S)-31) required prior methylation of the nitrogen atom and for this reason it was performed on the benzyl ether (2S,1'R,1''R)-32 (Scheme 10) [48]. Its reaction with methyl

• triflate afforded the respective aziridinium ion which was regioselectively reduced to (1R,2S,1'R)-33, a protected form of (−)-ephedrine (1R,2S)-31. Xestoaminol C ((2S,3R)-34) and 3-epi-xestoaminol C ((2S,3S)-34) represent a large family of naturally occurring 1-deoxysphingoids [49]. To finally prove their

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

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

• Stephan Scheeff and
• Dirk Menche

Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108

• stereoselective elimination and decarboxylation in situ. The corresponding aldehyde 22 was then homologated by an Abiko–Masamune anti-aldol addition [74] with ephedrine-derived ester 23, which proceeded with excellent yield and stereoselectivity. However, the subsequent removal of the sterically hindered chiral

Phosphated cyclodextrins as water-soluble chiral NMR solvating agents for cationic compounds

• Cira Mollings Puentes and
• Thomas J. Wenzel

Beilstein J. Org. Chem. 2017, 13, 43–53, doi:10.3762/bjoc.13.6

• -methylbenzylamine (4), β-methylphenethylamine (5), 1-methyl-3-phenylpiperazine (6), ephedrine (7), α-(methylaminoethyl)benzyl alcohol (8), 2-tert-butylamino-1-phenylethanol (9), α-(1-aminoethyl)-4-hydroxybenzyl alcohol (10), tyrosinol (11), 3-dimethylamino-2-methylpropiophenone (12), cis-(2-benzylamino

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• was done by Mukaiyama and Iwasawa in 1981 [28]. DCA reactions were performed on a series of α,β-unsaturated amides, which employed L-ephedrine as a chiral auxiliary (Scheme 2). Mechanistically, it was supposed that the Grignard reagent formed an internal chelate between the nitrogen and the oxygen on

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• into the nature of physiologically important aromatic amino alcohols such as ephedrine, pseudoephedrine, adrenaline, adrenalone and synephrine [75][76][77][78][79][80][81][82][83][84][85]. Some of this work took place even before the first analogous work on hydroxyamino acids by Sakami and Toennies [9

• [76][77][78][79][80][81][82][83][84][85]. Quite exotic reaction conditions were investigated for such salt acylations, as exemplified through the chemoselective O-acetylation of ephedrine hydrochloride with acetyl chloride in liquid SO2 (Scheme 15) [77]. More convenient was the O-acetylation of

• racemic ephedrine hydrochloride with acetyl chloride in HCl-saturated glacial acetic acid (Scheme 15) [77], the method that was later adopted for the O-acetylation of L-tyrosine (Scheme 2) [13]. A similar method, in which a steroidal amino alcohol was acetylated with acetic anhydride in a mixture of

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• degradation products which could be harmful to the human body. However, not every drug shows similar behavior when exposed to unfavorable conditions, e.g., nifedepine [2] and cyanocobalamin [3] degrade rapidly on exposure to light whereas ephedrine [4] shows a slower rate of photodegradation. Information

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

• dichlorides can be obtained either from chlorination of phosphonic acids [65][66] or from treatment of an allyl chloride such as 61 with phosphorus trichloride followed by hydrolysis to give 62 [15][67]. Reactions of unsymmetrical amines or aminoalcohols such as ephedrine with phosphonic acid dichlorides

• -monofluoroalkylphosphonic acids were synthesized by diastereoselective fluorination of phosphonamides bearing (−)-ephedrine as chiral auxiliary, originally introduced by Sting and Steglich for the synthesis of aminoalkylphosphonic acids [7] (Scheme 16). Thus, condensation of the phosphonic acid dichloride obtained from

• 134a,b with ephedrine yielded a separable mixture of diastereomeric phosphonamides, trans-135a,b and cis-136a,b. The fluorination with N-fluorobenzenesulfonimide (NFSI) of either trans-135a or cis-136a was found to be strongly dependant on the base used to generate the phosphonamidate anion. The best

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• (S)-4 to obtain 5, was achieved by treatment with N-methylpyrrolidine. An alternative method is based on ephedrine as a chiral auxiliary and was developed by Genêt and Jugé [36][37]. The key synthetic intermediates in this approach are 1,3,2-oxazaphospholidine boranes 7. These compounds are the

• result of the reaction between bis(diethylamino)alkylphosphine 6 and ephedrine, followed by protection with borane. The subsequent stereoselective ring opening of compound 7 with an organolithium reagent gives way to acyclic products 8 with retention of configuration at the phosphorus center. These

• of different starting oxazaphospholidine borane complexes 7 from (−)-ephedrine or (+)-ephedrine [38] or by starting from the same oxazaphospholidine borane adduct 7 and then changing the order of addition of the organolithium reagents (Scheme 2). Acidolysis with HCl of compounds 8a results in the

cis–trans Isomerization of silybins A and B

• Michaela Novotná,
• Radek Gažák,
• David Biedermann,
• Florent Di Meo,
• Petr Marhol,
• Marek Kuzma,
• Lucie Bednárová,
• Kateřina Fuksová,
• Patrick Trouillas and
• Vladimír Křen

Beilstein J. Org. Chem. 2014, 10, 1047–1063, doi:10.3762/bjoc.10.105

• benzodioxanes, e.g., the pair of benzodioxanes 17 and 18 synthesized from (+)-ephedrine; the natural benzodioxanes eusiderin (19) and eusiderin C (20) [17]; 21 and 22, isolated from Juniperus chinensis [18]; and benzodioxane 23 from Licaria chrysophylla [19] (Figure 5), for both the C-2, C-3 and C-10, C-11

Chiral recognition of ephedrine: Hydrophilic polymers bearing β-cyclodextrin moieties as chiral sensitive host molecules

• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1516–1519, doi:10.3762/bjoc.7.177

• Sabrina Gingter Helmut Ritter Institute of Organic Chemistry and Macromolecular Chemistry II, Heinrich-Heine-University, Universitätsstraße 1, 40255 Düsseldorf (Germany) 10.3762/bjoc.7.177 Abstract In this work we demonstrate chiral recognition of (+)- and (−)-ephedrine using a cyclodextrin

• -containing polymer. The supramolecular structures obtained by complexation of ephedrine and cyclodextrin were verified by 2-D ROESY NMR measurements. Dynamic light scattering showed clear differences in the mean coil size. Keywords: chiral recognition; cyclodextrins; ephedrine; host–guest interaction

• pharmaceutically active (+)- and (−)-ephedrine. Ephedrine is an alkaloid that functions as a decongestant, stimulant and appetite suppressant. Ephedrine is an aromatic amine and belongs to the group of amphetamines. We chose ephedrine as a model compound for the present investigation, as it exhibits chirality and

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Asymmetric synthesis of biaryl atropisomers by dynamic resolution on condensation of biaryl aldehydes with (−)-ephedrine or a proline- derived diamine

• Ann Bracegirdle,
• Jonathan Clayden and
• Lai Wah Lai

Beilstein J. Org. Chem. 2008, 4, No. 47, doi:10.3762/bjoc.4.47

• Ann Bracegirdle Jonathan Clayden Lai Wah Lai School of Chemistry, University of Manchester, Oxford Rd., Manchester M13 9PL, UK 10.3762/bjoc.4.47 Abstract Atropisomeric biaryl aldehydes undergo diastereoselective condensation with (−)-ephedrine and with a proline-derived diamine, with selectivity

• % yield. Hydrolysis and reduction of the major diastereoisomeric product of the reaction yields atropisomeric biaryls in >99:1 enantiomeric ratios. Keywords: atropisomer; biaryl; dynamic resolution; ephedrine; imdazolidine; oxazolidine; Introduction Atropisomeric biaryl compounds have proved to be among

• imidazolidines [25][27], ephedrine-derived oxazolidines [26][27], and, most extensively, sulfoxides [16][29][30][31]. These perform well when a powerful electronic or steric bias is evident about the atropisomeric bond over which control is applied [32], and in the case of atropisomeric amides have offered