Regioselective formal hydrocyanation of allenes: synthesis of β,γ-unsaturated nitriles with α-all-carbon quaternary centers

• Seeun Lim,
• Teresa Kim and
• Yunmi Lee

Beilstein J. Org. Chem. 2025, 21, 800–806, doi:10.3762/bjoc.21.63

• by the regio- and stereoselective allylation with p-toluenesulfonyl cyanide. The proposed methodology is efficient for accessing acyclic β,γ-unsaturated nitriles with α-all-carbon quaternary centers and achieves yields up to 99% and excellent regio- and E-selectivity. The reaction proceeds under mild

• efficiently constructed α-all-carbon quaternary centers on β,γ-unsaturated nitriles with excellent >98% regioselectivity and >98% (E)-selectivity. 1,1-Disubstituted allenes bearing silyl ether- and benzyl ether-tethered propyl groups were successfully converted into the desired nitriles 3a–c in yields ranging

• involves the regioselective nucleophilic attack of allylaluminum C on tosyl cyanide, which proceeds at the γ-position via six-membered ring transition state D, leading to the formation of the desired nitrile product. Transition state D is responsible for the E-selectivity observed in trisubstituted allenes

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• temperature (rt), the desired unsaturated ε-AA derivative 4a was obtained in 75% isolated yield (Table 1, entry 1). Isolation and NMR analysis demonstrated that this model reaction provided amino acid 4a with good E-selectivity and excellent regioselectivity (E/Z = 91:9, 1,4-/1,2-addition >20:1). Control

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• the construction of a range of δ-olefin-containing aliphatic nitriles with (E)-configuration selectivity. This new method features wide substrate scope, mild conditions, and direct N–O activation. Keywords: direct N–O activation; E-selectivity; nitrile synthesis; ring-opening cross-coupling; sulfuryl

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• configuration of the products by modifying the substituents on the nitrogen of the pyridinium salts. Further, the method showed a wide substrate scope for both the Z- and E-alkenylated products in which Z-selectivity was achieved when N-methylpyridinium salts were used and E-selectivity when N-benzylpyridinium

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

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

• transformations, prior to the cleavage of the Boc amide protecting group. The free amine 118 underwent an amidation with the TBS-protected (2Z,4S)-4-hydroxy-2-butenoic acid 12b to give 119. The modified Julia olefination of the aldehyde 73 with the anion derived from 119 proceeded with a high E-selectivity to

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

• took place away from the bulky alkyl chain, resulting in the observed E-selectivity. These outcomes were opposite to those obtained with the fluorinated substrate series, consistent with steric hindrance governing the non-fluorine containing oxetane reactions but electronics influencing and reversing

• 92:8 mixture of E/Z-9 was obtained in 74% yield. Finally, the reaction performed with TBAB in the presence of BF3·Et2O afforded only alkenes 9 with an excellent E-selectivity and in 66% yield (Table 3, entry 3). In this case, we presume 10 was not obtained because the benzyl ether is not nucleophilic

• analysis (see Supporting Information File 1). The attack of the bromide ion this time occurred from the side of the alkene hydrogen atom (cis attack) and away from the bulky phthalimido group giving solely product E-4d. Likewise, the reaction of the alkyl-substituted substrate 5 proceeded with excellent E

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• enantiopure trienyne or diene–diyne metathesis precursors were readily obtained from (S)-citronellal by a highly diastereoselective organocatalytic Michael addition. Erogorgiaene An exceptionally stereoselective synthesis of erogorgiaene (12) (95% E-selectivity) was reported by Hoveyda et al. [80]. They

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• excellent enantioselectivity and E-selectivity. In the AROCM of 75 with styrene (Scheme 8, reaction performed at −10 °C using 5 equiv styrene and 1 mol % of the catalyst), complex 204 gave the desired product 76 in >98% conversion, 93% ee and E/Z ratio > 30:1. Pursuing on this concept, the same group

• performances of these catalysts in AROCM transformations were comparable with those of the congeners 202–204 albeit they showed a lower E-selectivity. These systems were successfully employed

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• without any solvent (Table 1). In general, we noticed that more polar solvents (high dielectric constants) favour Z selectivity and a higher overall conversion, whereas the use of less polar or no solvent (lower dielectric constants) favour E selectivity and a lower overall conversion. As shown in Table 1

• ., at highest reactant concentration (Table 1). Further, our results show that the E selectivity and benzyl benzoate formation are observed together (when the dielectric constant of the LAG solvent is low). Therefore, if the benzyl benzoate formation follows the path presented in Scheme 1, perhaps the

• mechanism of the E selectivity is similar. The intermediate (Scheme 1) allows for a reaction pathway involving the formation of a six-membered ring instead of the traditional four-membered oxaphosphetane ring of the Wittig reaction. This six-membered ring may account for the higher E selectivity due to the

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• sulfenylated dienes by dehydration. A series of aryl thiols with different steric and electronic properties give high yields of the thiol–yne products. Noteworthy is the high E-selectivity of the resulting alkene. Dependent on the substitution pattern of the aryl thiol a ratio up to 60:1 was observed due to

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• Plus Reaction Station™. In line with DFT calculations by Kise et al. [12] and independently by Li and Janesko [21], the thermodynamically favored E-isomer was obtained as the main or sole product. The high E-selectivity was furthermore confirmed by 1H NMR analyses. The olefinic protons of the minor Z

• -to-Z isomerization was caused during acidic work-up or purification. When products 8a and 8j were isolated by extraction under neutral conditions, the high E-selectivity of the dehydration step was retained. After column chromatographic purification on silica gel, partial isomerization to the Z

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

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

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

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• ratio) resulted in a higher conversion and in a lower ene- and Z/E selectivity (Figure 10a). An increase in the solution flow rate (i.e., a decrease in τ) under a constant the H2/substrate molar ratio resulted in a conversion decrease, but in a selectivity enhancement (Figure 10b). A reproducible

(Z)-Selective Takai olefination of salicylaldehydes

• Stephen M. Geddis,
• Caroline E. Hagerman,
• Warren R. J. D. Galloway,
• Hannah F. Sore,
• Jonathan M. Goodman and
• David R. Spring

Beilstein J. Org. Chem. 2017, 13, 323–328, doi:10.3762/bjoc.13.35

• conversion of aldehydes to vinyl iodides, and has seen widespread implementation in organic synthesis. The reaction is usually noted for its high (E)-selectivity; however, herein we report the highly (Z)-selective Takai olefination of salicylaldehyde derivatives. Systematic screening of related substrates

• )-isomer was observed in the crude material (approx. ratio of (E)-7:(Z)-7 of 15:85 according to 1H NMR analysis, see Supporting Information File 1 for more information). There are several other examples of poor (E)-selectivity in the literature [8][9][10]; however, no detailed investigations as to the

• )-selectivity of 6, a number of ortho-substituted benzaldehydes were subjected to Takai olefination conditions; the results are summarised in Table 1 [11]. Unsubstituted benzaldehyde (Table 1, entry 1) gave the usual high (E)-selectivity expected of the Takai olefination (Takai et al. reported an (E):(Z)-ratio

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• rhodium carbenoid derived from diazophosphonoacetate 100 and alcohol 99 afforded intermediate 101 which was treated with lithium diisopropylamide and aldehyde 102 to afford alkene 103 with high E-selectivity. The following asymmetric copper(II)-catalyzed Claisen rearrangement [55], which is postulated to

Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate

• Piotr Wałejko,
• Michał Dąbrowski,
• Lech Szczepaniak,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204

• products (1-2 and 1-3). While the reaction of endo-nitrile 2 with alcohol 4 proceeded with lower Z/E selectivity (1.5:1) (Table 1, entries 13–15), the exo-isomer 1 reacted without any stereoselectivity (Table 1, entries 7–9). It is worth to note that the reactions of nitriles 1 and 2 promoted by the Grubbs

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• RRM with E-selectivity at the macrocyclic double bond. Along similar lines, compound 65f was treated with catalyst 1 in refluxing toluene followed by treatment with catalyst 2 to deliver desmethylmanshurolide 67 in 44% yield (Scheme 11). Cyclopentene systems In RRM with cyclopentene systems, the

SmI₂-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

• Nils Marsch,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2015, 11, 1700–1706, doi:10.3762/bjoc.11.184

• reaction of 23 with but-3-en-2-one in dimethylacetamide at 100 °C (76%). Enone 24 is a yellow solid, which had been obtained as an intermediate in the total syntheses of clavicipitic acid and 6,7-secoagroclavine in a four-step sequence starting from indole, but never in one step [37]. For achieving E

• -selectivity we attempted to adapt Schlosser's procedure for the olefination of aldehydes to the chloromethylenation of ketone 24 [38]. Selectivity towards the E-isomer was rather poor with an E/Z-ratio of 1.6:1 (Scheme 5). Separation of indiacen B (2) and its Z-isomer 26 was possible by semipreparative normal

Regioselective S_N2' Mitsunobu reaction of Morita–Baylis–Hillman alcohols: A facile and stereoselective synthesis of α-alkylidene-β-hydrazino acid derivatives

• Silong Xu,
• Jian Shang,
• Junjie Zhang and
• Yuhai Tang

Beilstein J. Org. Chem. 2014, 10, 990–995, doi:10.3762/bjoc.10.98

• (2b) and triphenylphosphine under very mild conditions (Scheme 2). To our delight, the reaction was completed in 30 minutes providing the anticipated trisubstituted hydrazine 3b in 90% isolated yield with excellent E-selectivity (E/Z > 20:1). To the best of our knowledge, this reaction represents the

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

• Armin Tröger,
• Teris A. van Beek,
• Martinus E. Huigens,
• Isabel M. M. S. Silva,
• Maarten A. Posthumus and
• Wittko Francke

Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72

• starting phosphorane and the known E-selectivity of the reaction [17], we assigned the (2E,4E)-configuration to the more abundant and later eluting series of stereoisomers and the (2E,4Z)-configuration to the less abundant one. The diastereomers could be well separated by GC, and only two members of the

Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica

• Danny Geerdink,
• Jeffrey Buter,
• Teris A. van Beek and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2014, 10, 761–766, doi:10.3762/bjoc.10.71

• allylic alcohol 17 in 90% yield, which in turn was oxidized to aldehyde 18 using Dess–Martin periodinane. Given that the conversion of 18 into 19 using a Wittig reaction had proven to be sluggish, we switched again to a Horner–Wadsworth–Emmons olefination, expecting to observe high E-selectivity. Indeed

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• respective methyl ester ylide 26 [25][26]. The reaction of phosphorane 24 with 11 under neutral conditions at 50 °C gave the desired diene 9a in very good 88% yield and in nearly perfect E-selectivity. The protection groups were removed from 9a under the previously established conditions to finally give

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• an in situ formed N-heterocyclic carbene. In all cases studied, they found both the anti/syn- and the Z/E-selectivity to be high (>20:1), but the chemical yield was varying. Highest yields (78–80%) were achieved with short alkyl chains (R = Me) or when R = phenyl. When the alkyl chain was lengthened

Homolytic substitution at phosphorus for C–P bond formation in organic synthesis

• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 1269–1277, doi:10.3762/bjoc.9.143

• the initial diorganophosphanyl radical (Scheme 7). The high E selectivity is attributable to kinetic control of the homolytic substitution, where R2P–PR2 preferentially approaches the vinyl radical from the roomier side. Although the transformation looks useful to construct an (E)-1,2