Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• , POB 35, 40351 Jyväskylä, Finland Stereochemistry Research Group of the Hungarian Academy of Sciences, H-6720 Szeged, Eötvös u. 6, Hungary, Interdisciplinary Centre of Natural Products, University of Szeged, Szeged, Hungary 10.3762/bjoc.17.80 Abstract A library of pinane-based 2-amino-1,3-diols was

• -amino-1,3-diols, which underwent a regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3. Keywords: 2-amino-1,2-diol; monoterpene; oxazolidin

• aminohydroxylation process starting from allylic carbamates usually carried out in the presence of potassium osmate [24][25][26][27][28]. In recent years, we have extensively studied the stereoselective synthesis, as well as catalytic and pharmacological applications of monoterpene-based 3-amino-1,2-diols, which are

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• are the reduction of prochiral ketones to chiral secondary alcohols, transamination of prochiral ketones to chiral amines, hydrolysis of symmetrical diesters to a chiral monoester, and esterification of prochiral diacids or diols. In desymmetrisation reactions, the enzyme initially produces the two

• prochiral diols. The enzyme reacts with an amino or acyl donor, releasing a first co-product, to give an aminated or acylated enzyme intermediate. This then reacts with the prochiral ketone or diol to generate the chiral products. “Ping-pong, first”. Followed in most lipase or esterase hydrolyses of

• prochiral diol esters. The enzyme reacts enantiospecifically with the ester to release a chiral product, leaving the acyl group attached to the active site. In a second stage the achiral acyl group undergoes hydrolysis by water. In the desymmetrisation of diols (and diacids, below) kinetic amplification can

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• reckoned that converting compound A to a more polar derivative could probably be a breakthrough. As common knowledge, the more polarized alcohols over EtOH are those diols or polyols, while MeOH was previously ruled out. Ethylene glycol, a basic chemical and the simplest diol, is slightly soluble in

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• )stoichiometric amounts of diol cleaving agents, other than EG (for instance, PD [239], DEG [240][241]). As a consequence, the depolymerisation step usually results in complex mixtures of oligomers. Moreover, reacting diols may be unstable under the reaction conditions adopted. Hence, if used in excess, a

• carried out using the above described soluble Ru(triphos)tmm/HNTf2 catalytic system [191]. Thus, poly(butylene terephthalate) (PBT) and polycaprolactone (PCL) were depolymerised into the corresponding (co)monomeric diols at 140 °C and 100 bar H2 in 1,4-dioxane

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

• Marek Kõllo,
• Marje Kasari,
• Villu Kasari,
• Tõnis Pehk,
• Ivar Järving,
• Margus Lopp,
• Arvi Jõers and
• Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

• 1,2-diols. Starting with a compound already possessing a hydroxy group at the position C11, only hydroxylation at C9 is needed. Commercially available corticosteroid cortisol already possesses a hydroxy group at the position C11, and therefore only hydroxylation at C9 is needed, making cortisol (1) an

• . Chemical oxidation of 9,11-dihydroxysteroids In the final step, the obtained trans-diols 5 and 6 were subjected to the chemical oxidation of the 9,11 carbon bond. Lead tetraacetate is a classic oxidant for the cleavage of vicinal diols. However, there are serious drawbacks when using Pb(OAc)4. In addition

• to its toxicity, the oxidation rate affording trans-diols was very slow in comparison to that for cis-diols. Using an even longer reaction time and stoichiometric amount of the reagent, diol 5 was not oxidized to the corresponding dicarbonyl compound 8. However, using NaOCl·5H2O as an oxidant [31

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• straightforward way to numerous fluorine-containing bicyclic compounds not previously available. The syn-dihydroxylation of compound 2f with the N-methylmorpholine-N-oxide (NMO)–OsO4 system resulted in a mixture of the corresponding diols 5 in a 36:64 ratio in 65% yield. Again, exo-dihydroxylation is to be

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• between thiol-functionalized β-CD and oleic acid-protected CdS nanocrystals [29]. These spherical CdS–CD nanoparticles could be employed as a photocatalyst for the dehydrogenation of alcohols to aldehydes (at a low concentration of the reactant of 1 mM, ≥92% selectivity) or diols (at a high concentration

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

• providing a mixture of monoprotected diols (−)-53 and 54 in a 10:1 ratio for the least sterically hindered alcohol in 98% yield. After chromatographic separation, (−)-53 underwent radical-induced Barton–McCombie deoxygenation (AIBN, Bu3SnH) to form (−)-55 in 82% yield. The double deprotection of (−)-55

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• related esters are relevant synthetic building blocks widely employed as cross-coupling reagents [14] as well as protecting groups for polyols and diamines [15][16]. Moreover, the reversible covalent interaction of boronic acids with specifically oriented cis-1,2 and 1,3-diols has been successfully

• nanoparticles, depending on the degree of substitution. For example, reaction of vicinal diols of dextran with hydrophobic PBA generates boronate esters, which form nanoparticles in water and are capable to host the anticancer drug doxorubicin [27]. In this report, the advantages of the milling process, such as

• ), by following a straightforward synthetic strategy recently reported by some of us [26]. Then, in order to assess the efficacy of the solid-state milling approach in the formation of boronate esters between the PBA moiety of 1 and the vicinal diols of dextran (Dex), both mechanochemical and

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• VIII was observed due to the difficulty of phosphorylation of the substrate by kinases [16]. The first kinase phosphorylation step is generally rate limiting, and the prior introduction of a phosphate or phosphonate function can circumvent this problem. The preparation of diols VIII was realized by

• olefination of a protected 1,3-dihydroxypropanone (Figure 3). However, the selective introduction of functional groups is not possible in these diols as the two hydroxy groups present similar chemical reactivity. Other approaches are available for a selective preparation of monofluoroalkenes including

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

• Esra Demir,
• Ozlem Sari,
• Yasin Çetinkaya,
• Ufuk Atmaca,
• Safiye Sağ Erdem and
• Murat Çelik

Beilstein J. Org. Chem. 2020, 16, 1805–1819, doi:10.3762/bjoc.16.148

• shorter reaction times under mild conditions using a simple purification method. Apparently, our protocol describes a reasonable methodology for the conversion of epoxides to protected 1,2-diols and 2-amino alcohols. Attention is drawn on these 1,2-oxygen and/or nitrogen units since they are present in

• using a safe, inexpensive, metal-free reagent, a simple purification method and shorter reaction times via a one-pot reaction. The study presents a useful method for one-pot conversion of epoxides to protected 1,2-diols and 2-amino alcohols in one reaction. In the computational part of the study, the

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• , or disulfonates of alkane-1,3-diols with sodium sulfide. The intramolecular substitution of 3-mercaptoalkyl halides or sulfonates is a similar strategy for the preparation of thietanes [12][13][14]. Alternatively, inter- and intramolecular photochemical [2 + 2] cycloadditions (thia-Paternò–Büchi

• )-1-tosylazetidine (22) with sodium sulfide followed by the detosylation with Mg in MeOH afforded 1,6-thiazaspiro[3.3]heptane (24) [36] (Scheme 4). 2.1.2 Synthesis via double nucleophilic displacements of disulfonates of alkane-1,3-diols: Considering that 6-amino-3-azaspiro[3.3]heptane was evaluated

• thietanes. Indeed, the direct cyclization of the 3-mercaptopropan-1-ol unit in 60 with Ph3P(OEt)2 as a reagent was realized in the synthesis of the spirothietane derivative 61 [44] (Scheme 14). Also, 1,3-diols were considered as precursors of γ-mercaptoalkanols. A Japanese group developed a new method to

Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles

• Lívia Dikošová,
• Júlia Laceková,
• Ondrej Záborský and
• Róbert Fischer

Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112

• isoxazolidines by means of dihydroxylation [9][10] and epoxidation [11][12] reactions. Regarding the stereochemistry, almost all of the realized additions proceed with an excellent trans stereoselectivity relative to the substituent at C-3, giving isoxazolidine-4,5-diols and isoxazolidinyl epoxides with a C-3/4

• , respectively, according to our procedure [7][10]. The compounds 5a and 5b were first converted into the isoxazolidine-4,5-diols by the treatment with potassium osmate/N-methylmorpholine N-oxide (NMO). The dihydroxylation reactions proceeded with an excellent trans selectivity with respect to the substituent at

• the C-3 carbon atom. The obtained products were benzoylated with benzoyl chloride/pyridine in the presence of DMAP to give the fully benzoylated isoxazolidine-4,5-diols 6a and 6b, which were subsequently treated with Et3SiH (3 equiv) and TMSOTf (2 equiv) in anhydrous CH2Cl2 at room temperature for 2 h

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• enantioselective and chemoselective oxidations of many organic compounds. Notably, the Gryko’s group recently described an enantio- and diastereoselective approach involving a porphyrin-based photooxygenation of aldehydes with sequential reduction to yield chiral diols in yields up to 91% and significant er (up to

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• energy [54]. The aromatic carbonyl compounds were dissolved in isopropanol and exposed to direct sunlight for 7–10 days to give the corresponding 1,2-diols 92 in high to moderate yield. The excitation of the carbonyl compound 87 was followed by hydrogen atom abstraction from the solvent 89, affording the

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• silyl ethers 89–92 (Scheme 18), thus showcasing the synergistic relationship between Pd and Cu catalysis [43]. Driven by the success of earlier results, the authors utilized 78 for reductive couplings between ketones 93 and imines 97 as electrophiles to form unsymmetrical 1,2-diols 94–96 and 1,2-amino

Asymmetric synthesis of CF₂-functionalized aziridines by combined strong Brønsted acid catalysis

• Xing-Fa Tan,
• Fa-Guang Zhang and
• Jun-An Ma

Beilstein J. Org. Chem. 2020, 16, 638–644, doi:10.3762/bjoc.16.60

• no enantioselectivity at all. As arylboronic acids have been harnessed to enhance the Brønsted acidity in asymmetric organocatalysis in combination with chiral diols or chiral aminoalcohols [40][41][42][43][44], we envisioned that the simultaneous use of arylboronic acids and chiral Brønsted acids

Synthesis of disparlure and monachalure enantiomers from 2,3-butanediacetals

• Adam Drop,
• Hubert Wojtasek and
• Bożena Frąckowiak-Wojtasek

Beilstein J. Org. Chem. 2020, 16, 616–620, doi:10.3762/bjoc.16.57

• the final product with ees not exceeding 95% [29], which is insufficient to be used as attractant for males of the Gypsy moth. In one of these methods the diols 5 and 7 were used as precursors in the synthesis of the cis-epoxides 1 and 3 (Scheme 1). A few methods for the synthesis of diols 5 and 7

• chiral centers for the synthesis of both enantiomers of disparlure 1 and 3 and monachalure 2 and 4. Compound 14 also offers the possibility of selective modification of one of the substituents as well as sequential introduction of aliphatic chains. After deprotection of the butanediacetal group, diols 5

• , giving compounds 22 and 23. The butanediacetal groups were then removed with p-toluenesulfonic acid and diols 5 and 6 were obtained with 79% and 64% yield, respectively. They were then used in a well-established three-step, one-pot procedure for epoxide ring closure [26][30][40][41]. Pure (+)-disparlure

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• reaction. In the presence of 2 mol % of the catalyst, the Hantzsch ester (HEH), as a hydrogen atom donor, under blue light irradiation, a large panel of ketones and aldehydes was readily converted into the corresponding 1,2-diols in moderate to excellent yields. The functional group tolerance of the

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• of xanthate esters with amines [18]. Furthermore, many methods have also been reported for the synthesis of cyclic thiocarbamates, and these include reactions of isothiocyanates with aldehydes in the presence of organocatalysts [19][20], reactions of vicinal diols with potassium thiocyanate [21

Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?

• Dominika Krištofíková,
• Juraj Filo,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2019, 15, 2948–2957, doi:10.3762/bjoc.15.290

• demanding ones, e.g., C6, C9 or C11. In addition, the acidity of the hydrogen-bond-donating moiety also ranges over a rather large area from pKa (H2O) 1 for phosphoric acid C10 to pKa (DMSO) 28 of diols C7 and C8. However, neither steric factors, nor the acidity of the H-bond-donor moiety seemed to play a

A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

• Daniel P. Pienaar,
• Kamogelo R. Butsi,
• Amanda L. Rousseau and
• Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

• solvents was successfully exploited using inexpensive KOt-Bu to obtain a variety of β-ketonitriles and trifunctionalized building blocks, including useful O-unprotected diols. It was discovered that lactones react to produce the corresponding derivatized cyclic hemiketals. Furthermore, the addition of a

• diols 1 and 8, thereby indicating that the hemiketals are still fully reducible under standard ketone reduction conditions. Purification of 6 afforded only a 10% overall yield of the diol 8, but the direct conversion of crude intermediate product 6 resulted in a doubling of the overall yield of the diol

• preparation of trifunctionalized building blocks (hydroxylated β-ketonitriles) and valuable β-ketonitriles (including enolizable compounds) in modest to good yields from lactones and esters. We are currently investigating novel applications of diols 1 and 8, as well as the application of this methodology for

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

• felt electrodes for successful application in asymmetric electroorganic transformations, Kashiwagi’s group came up with two distinct protocols for asymmetric electrochemical lactonization of differently substituted diols. In 1996, they disclosed an asymmetric electrocatalytic method for lactonization

• of methyl-substituted diols 51 on a TEMPO-modified graphite felt electrode in the presence of the chiral base (−)-sparteine (43) with excellent enantioselectivity (conditions A, Scheme 20) [51]. Later in 2003, they reported another protocol for a graphite felt electrode for asymmetric electrochemical

• lactonization of diols 51. However, in this method instead of a chiral base, they used 1-azaspiro[5.5]undecane N-oxyl 52 as a radical mediator for modifying the electrodes which resulted in optically active lactones 53 with enantiopurity of up to 99% (conditions B, Scheme 20) [52]. Chiral medium In this section

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland 10.3762/bjoc.15.205 Abstract Organocatalytic α-oxygenation of chiral aldehydes with photochemically generated singlet oxygen allows synthesizing chiral 3-substituted 1,2-diols. Stereochemical results indicate that the reaction in the presence

• of diarylprolinol silyl ethers is highly diastereoselective and that the configuration of a newly created stereocenter at the α-position depends predominantly on the catalyst structure. The absolute configuration of chiral 1,2-diols has been unambiguously established based on electronic circular

• dichroism (ECD) and TD-DFT methods. Keywords: 1,2-diols; ECD; enamines; organocatalysis; porphyrins; silyl ethers of diarylprolinols; singlet oxygen; Introduction Carbonyl compounds are one of the most important building blocks in organic synthesis. As a consequence, there is a constant need for new

Isolation and characterisation of irinans, androstane-type withanolides from Physalis peruviana L.

• Annika Stein,
• Dave Compera,
• Bianka Karge,
• Mark Brönstrup and
• Jakob Franke

Beilstein J. Org. Chem. 2019, 15, 2003–2012, doi:10.3762/bjoc.15.196

• -oxidative Grob fragmentation could make use of a push–pull mechanism between C-17 and C-22, building on acid–base catalysis. Alternatively, an enzyme could cleave the C17–C20 diol oxidatively. Several P450 enzymes have been reported to be capable of cleaving diols, presumably via a ferric peroxo