(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• acid motif, formation of the Weinreb amide 181 and Curtius rearrangement (to 182) were all possible. Comparative physicochemical and biological data for selected 1,3-cubanes and meta-benzene was reported by MacMillan and co-workers. They compared lumacaftor, one of the active compounds of the cystic

Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• TE-catalyzed marcolactonization [69]. The synthesis of linear peptide 34 commenced with the lactone opening of 26 to afford Weinreb amide 27. Following primary alcohol protection and amide reduction, the aldehyde 28 was coupled with iodide 29 to afford 30 via Nozaki–Hiyama–Kishi coupling, which was

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

• 7 and 8 were produced in high yields through LiAlH4 conditions or nucleophilic addition of methylmagnesium bromide. Moreover, product 4a could be easily transformed to unsaturated ε-amino amide 9 in total 76% yield. Likewise, Weinreb amide 10 was produced and further transformed into ketone 11 in 84

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

• on an intramolecular Mannich reaction that occurred in intermediate 31 (Scheme 4). Thus, thiolactam 26 was quantitatively converted to lactam 27, using the Belleau's reagent [43]. 27 was treated with Weinreb amide 33, prepared from commercially available bromoacetyl bromide [44] to provide the

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

• dienic relay unit, were prepared from Weinreb amide by an asymmetric pathway, were reacted with either the Grubbs second-generation catalyst, the Hoveyda–Grubbs second-generation catalyst, or the Zhan catalyst, the latter giving under the optimized conditions the highest yield of the expected

• (+)-virosaine B (19) from Weinreb amide by enyne metathesis as the key step. Access to virgidivarine (20) and virgiboidine (21) by an enyne metathesis route. Enyne metathesis approach to (−)-zenkequinone B (22). Access to C-aryl glycoside 23 by an intermolecular enyne metathesis/Diels–Alder cycloaddition

Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

• Shohei Mimura,
• Sho Mizushima,
• Yohei Shimizu and
• Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

• affected the stereoselectivities: Lower enantioselectivities were observed with benzyl ester 2g (Table 2, entry 8, >99% yield, 70% ee) and isopropyl ester 2h (Table 2, entry 9, >99% yield, 83% ee). In addition to the α,β-unsaturated esters, an α,β-unsaturated Weinreb amide 1i afforded the corresponding

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• bonds. C–H olefination Weinreb amide C–H olefination: Photoredox catalysts carry the reactions forward with high regioselectivity, good functional group tolerance, and with or without an external oxidant at low temperatures. However, without photoredox catalysts, the earlier syntheses suffered from the

• dependence on external oxidants and harsh reaction conditions [83][84]. In this context, in 2014, Fabry et al. reported the use of novel dual photoredox catalytic systems made up of photoredox catalyst 11 and a rhodium catalyst to carry out the Weinreb amide C–H olefination shown in Scheme 1 [85]. By using

• of 131 from 132. Plausible mechanism for the oxidative photocatalytic monochlorination using 5a. Plausible mechanism for the aerobic amination using acridinium catalyst 3a. Plausible mechanism for the synthesis of substituted benzonitrile derivatives in the presence of 3a. Weinreb amide C–H

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• listed above can be converted into various other synthetically useful groups, such as ketones, esters, carboxylic acids, and (Weinreb) amide groups. More recently, some works were reported, which showed that through a judicious selection of chiral ligands and a fine-tuning of the reactivities of both

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

• (and nitrile) were necessary to drive the reactions to completion as the acylated product is more acidic than the nitrile starting material. More recently, ester or Weinreb amide reactions with acetonitrile using lithium bases at low temperature [7], or similarly NaH at high temperatures [8], have been

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

• structurally related since they contain an (R)-1-aryl-2-propanamine moiety. The synthesis of the respective intermediates (R)-16 and (R)-17 commenced from the ester (2R,1'R)-5f and relied on arylation of Weinreb amide (2R,1'R)-18 to afford the aziridine ketone 19. Its highly stereoselective reduction with the

• synthesize N-Boc-norephedrine ((1R,2S)-29) the epimeric aziridine alcohol (2S,1'R,1''R)-28 was needed (Scheme 9) [47]. To this end the aziridine ketone (2S,1'R)-30 prepared from Weinreb amide (2S,1'R)-18 was reduced with a NaBH4/ZnCl2 mixture to give almost enantiomerically pure (>99:1) alcohol (2S,1'R,1''R

• stereochemistry, they were synthesized from the aziridine ketone (2S,1'R)-36 readily available from Weinreb amide (2S,1'R)-18 which already contained the required configuration at C2 (Scheme 11) [47]. Introduction of the 3R configuration in xestoaminol C and 3S in its epimer was achieved by stereoselective

Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds

• Hamada S. A. Mandour,
• Yoko Nakagawa,
• Masaya Tone,
• Hayato Inoue,
• Nansalmaa Otog,
• Ikuhide Fujisawa,
• Soda Chanthamath and
• Seiji Iwasa

Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31

• Hibarigaoka, Tempaku-Cho, Toyohashi 441-8580, Japan 10.3762/bjoc.15.31 Abstract A reusable and highly enantioselective catalyst for the intramolecular cyclopropanation of various diazo ester and Weinreb amide derivatives was developed. The reactions catalyzed by a water-soluble Ru(II)-Amm-Pheox catalyst

• diazoamide; Ru(II)-Pheox; water-soluble catalyst; Weinreb amide; Introduction Water-soluble transition metal complexes have been attracting increasing interest for catalytic applications because of their many advantages such as simple product separation, low cost, safety, and environmentally friendly

• ). Interestingly, Ru(II)-Amm-Pheox complex (cat. 2) catalyzes the asymmetric intramolecular cyclopropanation of diazo Weinreb amide (N-cinnamyl-2-diazo-N-methoxyacetamide) in a water/ether mixture, giving the corresponding lactam in high yield with high enantioselectivity (99% yield, 99% ee, Table 1, entry 6

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• give the (Z)-monofluoroalkene 67 as a single isomer (dr > 95:5). Conversion of the ester into the corresponding Weinreb amide, followed by addition of an organolithium reagent gave the corresponding ketone 69. Four further steps gave the ring skeleton for the proline residue of 71, i.e., formation of

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

• auxiliary proved demanding. The Menche group realized that a transformation to a Weinreb amide may be realized in an effective manner by an in situ activation of 24 with iPrMgCl [75], followed by a methylation of the free hydroxy group and introduction of the methyl ketone. This procedure proved superior to

• alcohol 49 in 76% over 2 steps [83]. Before TBS protection the Weinreb amide was generated and then conversed into the phosphonate 50 as a precursor for a Horner–Wadsworth–Emmons reaction. The olefination led to unsaturated ketone 52 in 79% yield. For the final fragment synthesis the ketone was reduced

• switched to the stannane 56 by lithium–halogen exchange and further treatment with Bu3SnCl [92] in 90% yield. The synthesis of the coupling partner 55 started with known Weinreb amide 64 which underwent a syn-selective palladium-catalyzed hydrostannylation and was then transformed to phosphonate 65 in good

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• Scheme 2. A Weinreb amide (1 equiv) and PhMgBr (2 equiv, Grignard’s reagent) are reacted in a 10 mL PFA coil at 60 °C for 5 min residence time. The reaction is quenched using aq HCl and the ketone is isolated with 97% yield. The aryl lithium compound is produced simultaneously by reacting aryl bromide (1

• steps makes it not a fully automated protocol. To make it such a platform, in Figure 4B, we have depicted a process instrumentation diagram for this scheme and subsequently discuss the details. The P&ID diagram in Figure 4B indicates that the flow rate of the Weinreb amide can be fixed at the desired

Solution-phase automated synthesis of an α-amino aldehyde as a versatile intermediate

• Hisashi Masui,
• Sae Yosugi,
• Shinichiro Fuse and
• Takashi Takahashi

Beilstein J. Org. Chem. 2017, 13, 106–110, doi:10.3762/bjoc.13.13

• serine, and the subsequent reduction of carboxylic acid derivatives such as ester [20][21][22][23][24][25][26][27], thioester [28], or Weinreb amide [29][30] to the aldehyde. In addition, Burke and co-workers reported an asymmetric hydroformylation of 2,2-dimethyl-2,3-dihydrooxazole for the synthesis of

Synthesis of polyhydroxylated decalins via two consecutive one-pot reactions: 1,4-addition/aldol reaction followed by RCM/syn-dihydroxylation

• Michał Malik and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2016, 12, 2602–2608, doi:10.3762/bjoc.12.255

• initiated from known iododerivatives 13 and 14, prepared from suitably protected carbohydrates (Scheme 3) [45][46][47]. Each of these compounds was subjected to the zinc-mediated fragmentation, followed by the Jones oxidation. The resulting acid (not purified) was transformed into a Weinreb amide. As a

β-Amino functionalization of cinnamic Weinreb amides in ionic liquid

• Yi-Ning Wang,
• Guo-Xiang Sun and
• Gang Qi

Beilstein J. Org. Chem. 2016, 12, 2372–2377, doi:10.3762/bjoc.12.231

• corresponding to [PhCHNHNs]+ (m/z = 291) could be clearly observed. The results indicated that the isolated products were both α-chloro-β-amino Weinreb amide derivatives. The assignments for the stereoselectivities were determined by the conversions of the diastereomers to their corresponding aziridines (Scheme

• the α-amino-β-chloro Weinreb amide derivative 8 (Scheme 5). This could be confirmed by mass spectroscopic analysis as well. In its mass spectrum, a prominent peak denoting [NsNHCHC(O)NMe(OMe)]+ (m/z = 302) was exclusively observed. Because compound 8 was derived from trans-aziridine, it should be the

• %). Typical procedure for the preparation of aziridines 7A and 7B: The β-amino Weinreb amide (6a-A or 6a-B, 70 mg, 0.16 mmol, 1.0 equiv), dichloromethane (5 mL) and triethylamine (0.1 mL) were loaded into an oven-dried vial. After stirring at room temperature for 24 h, the reaction mixture was concentrated to

Catalytic asymmetric formal synthesis of beraprost

• Yusuke Kobayashi,
• Ryuta Kuramoto and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2015, 11, 2654–2660, doi:10.3762/bjoc.11.285

• enantioselective intramolecular oxa-Michael reaction of an α,β-unsaturated amide mediated by a newly developed benzothiadiazine catalyst. The Weinreb amide moiety and bromo substituent of the Michael adduct were utilized for the C–C bond formations to construct the scaffold. All four contiguous stereocenters of

• decreased the reactivity and enantioselectivity. However, we found that the newly developed organocatalyst E, bearing increased HB-donating abilities, could improve both the reactivity and selectivity. In addition, the Weinreb amide moieties of the AIOM adduct were shown to be efficiently converted to β

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• step sequence of a Weinreb amide formation 228, epoxidation, and double addition of the vinyl Grignard 229 to generate the advanced intermediate 230. Finally, RCM of diolefin 230 under high dilution conditions afforded muscopyridine (73) (Scheme 37). Hagiwara and co-workers [173] have synthesized

Development of variously functionalized nitrile oxides

• Haruyasu Asahara,
• Keita Arikiyo and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2015, 11, 1241–1245, doi:10.3762/bjoc.11.138

• , amides, aldehyde, and ketone upon treatment with hydroxide, alkoxide, amine, diisobutylaluminium hydride and Grignard reagent, respectively. In these transformations, N-methyl-N-tosylcarboxamides behave like a Weinreb amide. Similarly, N-methyl-5-phenylisoxazole-3-carboxamide was converted into 3

• formyl moieties. Keywords: acylnitrile oxide; amide; formylnitrile oxide; functionalized nitrile oxide; Weinreb amide; Introduction Nitrile oxides are valuable synthetic synthons for the construction of heterocyclic compounds by cycloaddition reactions, which lead to the formation of two bonds in a

• -methylcarbamoyl functional group. The synthetic utility of nitrile oxide 2 will be indeed improved by converting the N-methylcarbamoyl group into other functionalities, i.e., nitrile oxide 2 may serve as an equivalent of nitrile oxides 4 having versatile functional groups (Scheme 1). Weinreb amide (N-methoxy-N

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

• conditions for the 1,4-addition of α,β-unsaturated amides and lactams (Scheme 17). Reaction 1 (Scheme 17) shows the rhodium-catalyzed 1,4-arylation of Weinreb amide 64 using phenyl[2-(hydroxymethyl)phenyl]dimethylsilanes. The authors were able to obtain the 1,4-addition product in quantitative yield in only

Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B

• Danielle L. Paterson and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 265–270, doi:10.3762/bjoc.11.29

• -ester 14 resulting from an additional Claisen condensation was the only isolated product. It was therefore decided to functionalise the ester moiety first. This was achieved by direct conversion of ester 12 into Weinreb amide 15 in 81% yield, followed by addition of lithiate 16 (formed from 1-bromo-3,4

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

• inseparable by normal chromatographic methods. The chiral backbone of 77 had a beneficial effect on the stereoselectivity of the olefination, with an improved E/Z ratio of 91:9 compared to the achiral analogue 24e (Table 1, entries 1 and 2). Employing phosphonate-Weinreb amide 78 and phosphonamide-Weinreb

• amide 79 not only afforded good E/Z ratios of 87:13 to 88:12 of 73b but also provided a product that could now be separated by column chromatography (Table 1, entries 3 and 4). Reduction of amide E-73b by LiAlH4 to aldehyde 74 and further reduction under Luche conditions delivered an allylic alcohol

Total synthesis of (−)-epimyrtine by a gold-catalyzed hydroamination approach

• Thi Thanh Huyen Trinh,
• Khanh Hung Nguyen,
• Patricia de Aguiar Amaral and
• Nicolas Gouault

Beilstein J. Org. Chem. 2013, 9, 2042–2047, doi:10.3762/bjoc.9.242

• rearrangement was then carried out by using silver nitrate in THF to give the intermediate ketene which was trapped with N,O-dimethylhydroxylamine to provide the corresponding Weinreb amide 1 in 84% yield over two steps. In the next step, the Weinreb amide 1 was added to a solution of O-protected 1-hexynol

• mmol, 3.8 equiv) at −78 °C under argon atmosphere. The reaction mixture was stirred for 45 min at −78 °C. Then, a solution of Weinreb amide 1 (800 mg, 3.3 mmol, 1 equiv) in 8 mL of dry THF was added dropwise at −78 °C. The reaction was stirred for 1 h. The reaction was warmed to −20 °C and stirred for

A reductive coupling strategy towards ripostatin A

• Kristin D. Schleicher and
• Timothy F. Jamison

Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175

• diastereoselectivity around 10:1, with further enhancement following silyl protection and purification. Although the silylated compound 60 proved to be reluctant to form the Weinreb amide, microwave irradiation allowed this process to proceed on a reasonable time scale. Grignard addition to the Weinreb amide afforded