BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• planar chirality into at least one of the subcomponents. One of the most important chiral molecular frameworks in general is the 1,1'-binaphthyl-2,2'-diol unit (BINOL, see Figure 1). BINOL is an axially chiral molecule with a high configurational stability and a well-established synthetic chemistry

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• ], the synthesis of axially chiral styrenes or vinylarenes has rarely been developed [90][91], due to their low rotational barrier and weak configurational stability. Moreover, the application of an organocatalytic kinetic resolution strategy to access axially chiral styrenes has rarely been reported. In

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• measurements, without any significant loss of the unpolarized emission intensity. This behavior, which precluded a quantitative analysis of the CPL properties, may be attributed to a photoinduced racemization process. The differences in configurational stability of boomerangs are reproduced by DFT calculations

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• the corresponding chlorophosphines gave the phosphine triazole ligands 120. Some ligands synthesized by the same route are included in Figure 2 (121–123). P-stereogenic phosphine ligands are difficult to synthesize because of low configurational stability and less availability of P-stereogenic

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

• of chemical and configurational stability was achieved by introducing N,N-dibenzylserinals 4 [10]. Another important strategy of asymmetric synthesis relies on chiral auxiliaries, i.e., a specially selected homochiral part of a starting material governing the stereoselectivity of subsequent reactions

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• lactone product). Sequestering of intermediates by the ACP domains has been proposed as a source of configurational stability at C-2 [82]. However, as all direct study of this question to date by NMR has failed to reveal any direct contact between modular PKS ACP domains and their attached substrates [83

Synthesis and immunological evaluation of protein conjugates of Neisseria meningitidis X capsular polysaccharide fragments

• Laura Morelli,
• Damiano Cancogni,
• Marta Tontini,
• Alberto Nilo,
• Sara Filippini,
• Paolo Costantino,
• Maria Rosaria Romano,
• Francesco Berti,
• Roberto Adamo and
• Luigi Lay

Beilstein J. Org. Chem. 2014, 10, 2367–2376, doi:10.3762/bjoc.10.247

• benefit of the easy availability of the α-hemiacetal 6 was illustrated by the improved synthesis of the spacer-linked MenX monomer 1 (Scheme 2). The PivCl-mediated coupling of 6 with compound 8 [35][36] provided the glycosylphosphodiester 9 as a pure α-anomer, demonstrating the configurational stability

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

• halophosphines and their weak configurational stability. P-stereogenic chlorophosphines racemize easily even at room temperature [30]. Enantiopure P-stereogenic compounds can be synthesized via a diastereoselective nucleophilic substitution at phosphorus utilizing chiral auxiliaries. Diastereomeric intermediates

• stereoselective synthesis of chiral chlorophosphine boranes 11a [39]. The borane complex has a good configurational stability with borane as a protecting group, in contrast to chlorophosphines that can undergo inversion at the phosphorus center [30]. They allow the synthesis of a variety of P-chiral tertiary

Synthesis and stereochemical assignments of diastereomeric Ni(II) complexes of glycine Schiff base with (R)-2-(N-{2-[N-alkyl-N-(1-phenylethyl)amino]acetyl}amino)benzophenone; a case of configurationally stable stereogenic nitrogen

• Hiroki Moriwaki,
• Daniel Resch,
• Hengguang Li,
• Iwao Ojima,
• Ryosuke Takeda,
• José Luis Aceña and
• Vadim A. Soloshonok

Beilstein J. Org. Chem. 2014, 10, 442–448, doi:10.3762/bjoc.10.41

• -phenylethylamine and 2-aminobenzophenone were prepared by alkylation of the nitrogen atom. Upon reaction with glycine and a Ni(II) salt, these ligands were transformed into diastereomeric complexes, as a result of the configurational stability of the stereogenic nitrogen atom. Different diastereomeric ratios were

• configurational stability of the stereogenic nitrogen. 2) The steric bulk of the substituent R on the α-phenylethylamine residue has a negative effect on the reaction rates and a positive influence on the stereochemical outcome. 3) The optimal size of the R group is n-Pr or Bn. 4) Synthesis of this type of Ni(II

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• the proof of the configurational stability of a chiral center in the vicinity of the alkyne. For this purpose, optically active 1j was prepared. As next step, its reactivity in the gold(I)-catalyzed hydroarylation study was investigated (Scheme 3). Though the regioselectivity was lower and requires

Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119

• irradiation of the azobenzene fragment allows the reopening of the azobenzene gate. Unidirectional photoisomerization The process, trans to cis isomerization, generates helicoidal chirality, such that the isomer can adopt a helicoidal geometry with P or M chirality. The configurational stability of cis

Carbamate-directed benzylic lithiation for the diastereo- and enantioselective synthesis of diaryl ether atropisomers

• Abigail Page and
• Jonathan Clayden

Beilstein J. Org. Chem. 2011, 7, 1327–1333, doi:10.3762/bjoc.7.156

• diethyl ether. Enantioselective deprotonation of one of the two benzylic positions leads to atropisomeric products with ca. 80:20 e.r.; an electrophilic quench typically provides functionalised atropisomeric diastereoisomers in up to 97:3 d.r. Keywords: configurational stability; diaryl ether

• organolithium compounds having varying degrees of configurational stability [17][18], and in our studies on ureas and amides we were able to identify correlated inversion processes linking configurational inversion at organolithium centres with conformational inversion of atropisomeric chirality by bond

• configurationally unstable in ether on the macroscopic timescale [1], although Hoffmann detected microscopic configurational stability [30]. To demonstrate that the organolithium intermediates here do have some configurational stability, we treated samples of 13e of different diastereoisomeric and enantiomeric

Stereogenic boron in 2-amino-1,1-diphenylethanol-based boronate–imine and amine complexes

• Sebastian Schlecht,
• Walter Frank and
• Manfred Braun

Beilstein J. Org. Chem. 2011, 7, 615–621, doi:10.3762/bjoc.7.72

• acyloxyboranes 3 [13][14][15][16] with electron with-drawing substituents X (Scheme 1) that turned out to be crucial to the configurational stability at boron, and recently, in boronate complexes of boradiazaindacene [17]. Pursuing the concept of tridentate ligands derived from 2-amino-2,2-diphenylethanol we

• effect is observed in the CD spectrum of the enantiomer of 8 that is eluted at lower retention time, the (R)-configuration is attributed to this enantiomer by analogy. As we were interested in whether or not the configurational stability differs in boronate–imine complexes 4 and 8 on the one hand and

• measured to be 4.1·10−4 s−1 and the racemization barrier ΔG‡ amounted to 101.0 kJ·mol−1 [24]. The corresponding values for boronate–imine complexes 4 varied from 105–110 kJ·mol−1, indicating that the change from the imine to the amine ligand does not alter the configurational stability at boron to any

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• derivatives: 1) The substrate 67 must be available in an enantiomerically pure form, 2) The lithiated intermediate 68 must be configurationally stable, and 3) Electrophilic addition to give 69 must proceed with either complete retention or complete inversion of stereochemistry. 2.2.1 Configurational stability

• presence of (−)-sparteine 74 (Scheme 26) were attempted [64]. Trapping the lithiated intermediate 75 with electrophiles gave products with poor enantioselectivities, but the results gave no indication of the configurational stability of the intermediate organolithium 75. To establish the factors governing

• that the lithio derivative of thiocarbamate 77 must be configurationally labile since the product is non-racemic. In order to induce greater configurational stability, thiocarbamate 79, with increased steric bulk, was prepared. A sample of 79 with an enantiomeric ratio of 73:27 was lithiated with sec

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• , corresponding to a half-life of 4.5 hours for racemization [28]. The high stability of the configuration even at such an elevated temperature allows BINOL to be used in a variety of synthetic applications. The configurational stability of 20b and 20c, which could be regarded as 2,2'-disubstituted 1,1

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

Synthesis of (–)-Indolizidine 167B based on domino hydroformylation/cyclization reactions

• Giuditta Guazzelli,
• Raffaello Lazzaroni and
• Roberta Settambolo

Beilstein J. Org. Chem. 2008, 4, No. 2, doi:10.1186/1860-5397-4-2

• transformation is completely stereospecific and it does not involve the chiral center. An evaluation of the enantiomeric excess of both unconverted 1 and produced 3 was carried out in order to test the configurational stability of these structures under hydroformylation conditions. Interestingly 1 showed, at all

• -alkyl intermediates and carries on with the intramolecular cyclodehydration of the formed linear aldehyde followed by hydrogenation. All steps occur with almost complete configurational stability and the final indolizine has the same optical purity as the starting material. The hydroformylation