Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• allomorphism, the elucidation of the structure of cellulose I, awaited the mature developments of large scale facilities of synchroton and neutron sources, and the mastering of deuteration methods of the intra-crystalline regions of the native cellulose samples without altering the overall structural integrity

Aggregation behaviour of a single-chain, phenylene-modified bolalipid and its miscibility with classical phospholipids

• Simon Drescher,
• Vasil M. Garamus,
• Christopher J. Garvey,
• Annette Meister and
• Alfred Blume

Beilstein J. Org. Chem. 2017, 13, 995–1007, doi:10.3762/bjoc.13.99

• ) was followed. The deuteration of alkyl chains in phospholipids usually causes a shift of the main transition by about 5 K to lower temperatures, as shown by Petersen et al. [57]. At T = 10.9 °C, the frequency of νs(CH2) is at 2850.8 cm−1, which is comparable to the frequency of νs(CH2) of the pure PC

New approach toward the synthesis of deuterated pyrazolo[1,5-a]pyridines and 1,2,4-triazolo[1,5-a]pyridines

• Aleksey Yu. Vorob’ev,
• Vyacheslav I. Supranovich,
• Gennady I. Borodkin and
• Vyacheslav G. Shubin

Beilstein J. Org. Chem. 2017, 13, 800–805, doi:10.3762/bjoc.13.80

• and a high degree of deuterium incorporation were achieved. The procedure was applied for several 4-R-1-aminopyridinium cations (R = H, Me, OMe). Keywords: deuteration; 1,3-dipolar cycloaddition; pyrazolo[1,5-a]pyridine; 1,2,4-triazolo[1,5-a]pyridine; Introduction Isotopically labeled compounds find

• years deuteration became also an efficient tool in drug design [6]. Pyrazolo[1,5-a]pyridine and 1,2,4-triazolo[1,5-a]pyridine scaffolds attracted significant attention to the medicinal chemistry community during the past decade. For example, pyrazolo[1,5-a]pyridine derivatives were used in the design of

• dimethyl acetylenedicarboxylate (2a, DMAD) in MeCN D-labeled pyrazolo[1,5-a]pyridine 3 was obtained in 70% yield (Table 1). The deuteration at room temperature even for 24 h led to a significantly lower degree of deuteration (DD, 20%). Salt 1b gave the corresponding 5-CD3-7-D-pyrazolopyridine 5 along with

Cp₂TiCl/D₂O/Mn, a formidable reagent for the deuteration of organic compounds

• Antonio Rosales and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2016, 12, 1585–1589, doi:10.3762/bjoc.12.154

• experimental conditions and with great economic advantages. Keywords: deuteration; deuterium atom transfer; radical and/or organometallic chemistry; titanocene; Introduction Deuterium is a stable isotope of hydrogen with 0.015% natural abundance broadly used in organic chemistry, pharmacology, organometallic

• develop efficient procedures for the preparation of deuterated compounds, several methodologies of deuteration have been reported [5]. One of the first procedures reported was the acid- or base-catalyzed exchange of enolizable protons for deuterium. However, in order to achieve high isotopic purities

• for deuteration [7]. The principal disadvantage of the use of reducing agents labelled with deuterium is the high cost of these reagents and the handling of highly flammable substances. The use of palladium metal and D2O is a useful and efficient methodology for H/D exchange in aliphatic and benzylic

Tandem processes promoted by a hydrogen shift in 6-arylfulvenes bearing acetalic units at ortho position: a combined experimental and computational study

• Mateo Alajarin,
• Marta Marin-Luna,
• Pilar Sanchez-Andrada and
• Angel Vidal

Beilstein J. Org. Chem. 2016, 12, 260–270, doi:10.3762/bjoc.12.28

• monodeuterated acetal-fulvene 20 bearing the deuterium atom at C4. This species converted into a 2:1 mixture of the monodeuterated regioisomers 21 and 22 as the only isolated reaction products (Scheme 6). In both compounds, the deuteration percentage at their respective C4 and C9 positions was determined, by 1H

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• tributyltin hydride or THF was tested and THF proved to be a more efficient hydrogen atom donor. The addition of excess pyridine to MeCN/THF solution of diazonium tetrafluoroborates 3a or 3b led to an efficient hydrodediazoniation and the formation of (pentafluorosulfanyl)benzene (6). Deuteration experiments

Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides

• Armando Navarro-Vázquez

Beilstein J. Org. Chem. 2015, 11, 1441–1446, doi:10.3762/bjoc.11.156

• ). Nonetheless, the above results suggest that varying the reaction conditions (perhaps solvent polarity) could eventually lead to the observation of the allenimides. NMR deuteration studies could be of help to experimentally eliminate possible kinetic effects in the observed lack of reactivity [19]. Having

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• . Absence of the peak at δ 4.26 (singlet) in 1H NMR suggest the incorporation of deuterium and a triplet at δ 71.0, arising from C–D coupling, instead of sharp peak at δ 71.3 in 13C NMR further confirmed the deuteration at the chlorine-attached carbon atom in 5n (Scheme 3). Further, in order to understand

Pyrrolidine nucleotide analogs with a tunable conformation

• Lenka Poštová Slavětínská,
• Dominik Rejman and
• Radek Pohl

Beilstein J. Org. Chem. 2014, 10, 1967–1980, doi:10.3762/bjoc.10.205

• ), exist at a very low pD value (<3) as free phosphonic acids with a deuterated pyrrolidine nitrogen atom (Figure 6). The phosphonic acid moiety goes through a two-stage deuteration/dedeuteration transition at pD ~ 3 and 5 and the pyrrolidine nitrogen atom stays deuterated until pD ~ 9. This suggests that

• the compounds exist as zwitterions with a hydrogen bond between the negatively charged phosphonate moiety and the positively charged pyrrolidine nitrogen atom in the range of pD 3–9. The pD titration experiments have also revealed the deuteration/dedeuteration of adenine and thymine nucleobases. In

• , the nucleobase and the endocyclic phase angles for the purposes of the conformational analysis. The aliphatic part (pyrrolidine protons) of the 1H NMR spectra of 9 measured in D2O at different pD values. Changes of selected 1H and 13C chemical shifts of 9 upon pD change. The deuteration equilibria of

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• . Synthesis of compounds 5. Initial mechanistic proposal to explain the formation of compounds 5 that was ruled out by deuteration experiments. Alternative mechanistic proposal based on a carbon monoxide-induced deoxygenation. Solvent screen and temperature optimization for the synthesis of compound 5f. Scope

Regioselective carbon–carbon bond formation of 5,5,5-trifluoro-1-phenylpent-3-en-1-yne

• Motoki Naka,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2013, 9, 2182–2188, doi:10.3762/bjoc.9.256

• 6a (Scheme 2). In the case of 5 and 6, electrophiles were incorporated without stereochemical contamination in all instances. For obtaining further mechanistic proofs for the present reaction, we have planned to capture the intermediary anionic species with the aid of the usual deuteration technique

• elucidated as follows: deuteration would quickly occur to afford 4-d1 and 4-d2 whose proportion would reflect the ratio of 4-Li1 and 4-Li2. On the other hand, less reactive aldehydes should be captured more slowly and the product preference of 5 to 6 would be kinetically determined by their activation energy

• was slow. This important information allowed us to reconsider our previously proposed mechanism as shown in Scheme 5. A part of 1H NMR chart of 4 and its deuterated mixture. Proposed reaction mechanism between 1 and MeLi. Furan synthesis from a mixture of 5a and 6a. Deuteration of anionic species from

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• spectrum the H-1’ signal appeared as a doublet centered at 4.82 ppm with J1,2 = 3.9 Hz, characteristic of α-D-glucopyranosides. The multiplet centred at 4.32 ppm, assigned to H-3, showed coupling with the HO-3 (δ 4.62, J3,HO = 4.3 Hz). On deuteration this signal disappeared and the H-3 signal collapsed

Alkenes from β-lithiooxyphosphonium ylides generated by trapping α-lithiated terminal epoxides with triphenylphosphine

• David. M. Hodgson and
• Rosanne S. D. Persaud

Beilstein J. Org. Chem. 2012, 8, 1896–1900, doi:10.3762/bjoc.8.219

• -induced method to deoxygenate epoxides [43], which in the case of deuteration would provide a regiospecific and potentially stereoselective entry to 1-deuterated terminal alkenes [44][45]. Use of a slightly higher molecular weight epoxide, 1,2-epoxydodecane (13) to facilitate product isolation, gave

Self-assembly of Ru₄ and Ru₈ assemblies by coordination using organometallic Ru(II)₂ precursors: Synthesis, characterization and properties

• Sankarasekaran Shanmugaraju,
• Dipak Samanta and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34

• the reported procedure [21]. NMR spectra were recorded on a Bruker 400 MHz spectrometer. The chemical shifts (δ) in the 1H NMR spectra are reported in ppm relative to tetramethylsilane (Me4Si) as the internal standard (0.0 ppm) or the proton resonance resulting from incomplete deuteration of the NMR

Use of mixed Li/K metal TMP amide (LiNK chemistry) for the synthesis of [2.2]metacyclophanes

• Marco Blangetti,
• Patricia Fleming and
• Donal F. O'Shea

Beilstein J. Org. Chem. 2011, 7, 1249–1254, doi:10.3762/bjoc.7.145

• selective site of metalation should be the more acidic 2-methyl position [26]. This was confirmed by 2H NMR, which showed that incorporated deuterium was above 90% in the 2-methyl position with less than 10% in the 4-methyl group and no detectable aryl deuteration (Figure 2). A similar experiment was

• deuteration gave the di-deuterated product D2-6f. 2H NMR analysis showed no aryl or bridging methylene deuteration, with deuterium incorporated only into the two non-equivalent benzylic methyl positions (Figure 3). With the benzylic metalation confirmed, the second step to complete the [2.2]metacyclophane

Gelation or molecular recognition; is the bis-(α,β-dihydroxy ester)s motif an omnigelator?

• Peter C. Griffiths,
• David W. Knight,
• Ian R. Morgan,
• Amy Ford,
• James Brown,
• Ben Davies,
• Richard K. Heenan,
• Stephen M. King,
• Robert M. Dalgliesh,
• John Tomkinson,
• Stuart Prescott,
• Ralf Schweins and
• Alison Paul

Beilstein J. Org. Chem. 2010, 6, 1079–1088, doi:10.3762/bjoc.6.123

• deuteration would be expected. The nine sharp features between 150 and 800 cm−1 arising from the d-toluene in the gelled samples are of considerably more interest, indicating that the average environment of the toluene methyl groups are significantly different. This difference may have a number of origins

• , one of which may be as a result of deuteration, but it is much more likely due to unavoidable thermal histories of the two samples (cooling rates, time elapsed since the initial freezing). Further, it is not possible to normalize the spectra such that all of these nine bands overlap completely with

α,β-Aziridinylphosphonates by lithium amide-induced phosphonyl migration from nitrogen to carbon in terminal aziridines

• David. M. Hodgson and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2010, 6, 978–983, doi:10.3762/bjoc.6.110

• : lithiation-deuteration of N-diphenylphosphinylaziridine 10 gave the anticipated deuterated aziridine 11 (70%), along with the rearranged aziridine 12 (25%) [24] (Scheme 3). Results and Discussion So as to examine the migration chemistry outlined in Scheme 1, access to N-phosphonate terminal aziridines 1 was

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

Part 2. Mechanistic aspects of the reduction of S-alkyl- thionocarbonates in the presence of triethylborane and air

• Florent Allais,
• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 46, doi:10.1186/1860-5397-3-46

• an attempt to gain information about the mechanism, we performed deuteration experiments (Figure 1 and Table 1). Most of the results reported herein concern the reduction of xanthate 1a [see Supporting Information File 2, Supporting Information File 3, and Supporting Information File 4]. This

• conceals several subtleties. In our quest for the origin of the transferred hydrogen, we demonstrated by unambiguous deuteration experiments that three types of sources are implicated. The first one relies on hydrogen donation from an O-H group (presumably complexed to the trialkylborane). This O-H group

• reduction of compound 1a in C6H6 at 20°C. Preparation of Et3B-d15. Deuteration experiments Reduction of xanthate 1a in the presence of deuterated O-ethyl S-ethyl dithiocarbonates 3–5 in C6H6. Reduction of xanthate 1a with Et3B-d15, Et3B-d6 and Et3B-d9 in C6H6. Supporting Information Supporting Information