Chiral cyclopropenimine-catalyzed enantioselective Michael reactions of phenol and benzofuran-derived α,β-unsaturated pyrazolamides with benzophenone-imine of glycine esters

• Ya Bai,
• Xue-Ying Wang,
• Si-Kai Zhu,
• Yan-Ting Shen,
• Sheng-Yong Zhang and
• Ping-An Wang

Beilstein J. Org. Chem. 2026, 22, 888–896, doi:10.3762/bjoc.22.69

• adjacent stereocenters, which was obtained from in-situ acidic hydrolysis and lactamization of the corresponding Michael product. Keywords: α,β-unsaturated pyrazolamide; chiral cyclopropenimine; glutamic acid; lactamization; Michael addition; Introduction Phenols and benzofurans are feedstock chemicals

• catalyst CSB-1 was released and entered the next catalytic cycle. The pyroglutamic acid esters 7 were obtained through in-situ acidic hydrolysis and lactamization of 6 [14]. Three Michael products 6d, 6d’ and 6h were treated under 4 N HCl in DCM to give 3-substituted pyroglutamic acid esters 7d, 7d’ and 7h

• -conformation and the absolute configurations of 7d’ was unambiguously assigned as 2S and 3S, this means that the benzophenone-imine group and bromophenoxymethyl group should be arranged on the same side of the longest carbon chain to be syn before lactamization, therefore, the absolute configuration of 6d’ was

Recent advancements in the synthesis of Veratrum alkaloids

• Morwenna Mögel,
• David Berger and
• Philipp Heretsch

Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206

• formation and reductive coupling with an aldehyde made accessible β-amino alcohol 60 over two steps. A cascade reaction occurred upon treatment with HCl in acetone followed by treatment with KOH. Indeed, a tandem 5-exo-trig cyclization, sulfinyl removal, and lactamization occurred in one-pot. Finally

• reductive coupling lead to β-amino alcohol 71, which was then transformed through similar conditions (see cyclopamine paragraph) via a tandem sulfinyl removal/lactamization, and subsequent lactam reduction, to veratramine (13). In particular, this semisynthesis furnishes veratramine in 13 steps in the

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• congested structures in complex bicyclic systems. 2 Alkaloids 2.1 Lycoplatyrine A In 2020, Sarpong's group disclosed their progress toward a robust and broadly applicable strategy for the C–H functionalization of piperidines and related saturated N-heterocycles. This approach involves lactamization via

Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions

• Xiaoming Ma,
• Zijie Gao,
• Jiawei Niu,
• Wentao Shao,
• Shenghu Yan,
• Sai Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167

• ]. We herein propose a one-pot synthesis involving an Ugi–azide 4-component (4-CR) reaction followed by lactamization and azide–alkyne cycloaddition for assembling triazole-fused and tetrazole-tethered 1,4-benzodiazepines 7 and triazole-, tetrazole-, and piperazinone-fused 1,4-benzodiazepines 8 (Scheme

• , the reaction of 0.2 mmol each of 1a and 2a led to the formation of Int-I which then reacted with 0.2 mmol each of 9 and 4 to form 1,5-DS-T 5b which consequently underwent lactamization to form 6a followed by an intramolecular click reaction to afford highly condensed polycyclic product 8a in 92

• . However, the reaction of 2-azido-5-bromobenzaldehyde (1d) gave only a trace amount of product 8h. Instead, compound 8h', an intermediate without lactamization, was isolated in 59% yield. It is likely that the bromo group on the phenyl ring interfered with the lactamization process. Two control reactions

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

Further elaboration of the stereodivergent approach to chaetominine-type alkaloids: synthesis of the reported structures of aspera chaetominines A and B and revised structure of aspera chaetominine B

• Jin-Fang Lü,
• Jiang-Feng Wu,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2025, 21, 2072–2081, doi:10.3762/bjoc.21.162

• generation of our synthetic strategy to chaetominine-type alkaloids featuring two modifications of the last step of our 4 to 6-step approach. Firstly, by employing EDCI/HOBt as the coupling system for the last step of the one-pot O-debenzylation–lactamization reaction, the overall yield of our previous total

• , we have communicated the revision of the structure of versiquinazoline H to 11. During and after the latter work, we undertook further investigation on the last step of our approach to chaetominine-type alkaloids, namely, the lactamization reaction for synthesizing 3,14-cis-chaetominines and the DMDO

• Improved five-step total synthesis of (–)-isochaetominine A In our recent communication on the synthesis of versiquinazoline H (11) [65], we uncovered that the employment of EDCI/HOBt as the coupling system for the last step, namely, the O-debenzylation–lactamization reaction, afforded much higher yields

Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• cyclization of tryptamine 26a with keto-diester intermediate 27 followed with a lactamization reaction in one-pot to access the γ-lactam moiety in product 28a, which was obtained after Boc protection. Base-promoted aldol reaction of lactam 28a with aldehyde 29 gave rise to alcohol 30a, which subsequently

Catalytic asymmetric reactions of isocyanides for constructing non-central chirality

• Jia-Yu Liao

Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129

• as the cross-partner [54]. By employing Ag2CO3 and L6 as the catalyst, axially chiral N-arylindoles 55 were synthesized in 36–94% yield with 26–90% ee (Scheme 8d). Building on such results, a one-pot procedure involving DKR, hydrolysis, and lactamization was developed, enabling a practical synthesis

A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones

• Ashutosh Nath,
• John Mark Awad and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92

• as HIV inhibitors [14]. The imidazo[1,2-a]pyridine ring can be readily synthesized by the GBB reaction [10][15], while the isoquinolinone ring is commonly generated by a cyclative lactamization process. Performing a GBB reaction followed by an intramolecular amidation is a good approach for making

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• azlactone enol through its Si-face to the azadiene leads to intermediate B, which undergoes an intramolecular lactamization delivering the desired product. Conclusion In this review, an overview of the recent advances of cyclization reactions involving α,β-unsaturated imines catalyzed by non-covalent

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• -methoxyphenyl (PMP)-protected imines 21 (Scheme 6A). By varying the reaction conditions, the syn-anti and the syn-syn diastereomers can be prepared with good yields and excellent stereoselectivity. Using nitroacrylate 23, the authors have also demonstrated a tandem conjugate addition/nitro-Mannich/lactamization

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• investigated the Ru-catalyzed ring-opening/lactamization of azabenzonorbornadiene derivatives 30 with arylamides 116 (Scheme 21) [64]. Weinreb amides outperformed other arylamides, likely serving as a better directing group for the initial aryl-C–H activation. While the scope of functionalized aryl Weinreb

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• mesoxalic ester amide 102 in a Friedel–Crafts reaction followed by a spontaneous lactamization to give (rac)-cladoniamide G (103). The mesoxalic ester amide 102 was synthesized from malonyl chloride 104 through amidation and Regitz diazotransfer, yielding diazo compound 105. Subsequent oxidation and

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• ]indolylvincoside 12 (de = 85%) [14]. In situ lactamization of 12 under basic conditions (10% Na2CO3) generated stable polycyclic compound 13 in 70% yield (Scheme 5A). In a separate report published in 2020, the same research group disclosed that water could act as both catalyst and solvent in the Pictet−Spengler

Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines

• Zara M. Seibel,
• Jeffrey S. Bandar and
• Tristan H. Lambert

Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134

• -substituted glutamate derivatives is via the Michael addition of α-amino ester enolates to acrylate acceptors. These products can also be easily converted to pyroglutamates by lactamization [28][29][30]. Although the use of substituted amino ester derivatives for the enantioselective α-alkylation has been

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

• Tetsuya Sengoku,
• Koki Makino,
• Ayumi Iijima,
• Toshiyasu Inuzuka and
• Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

• -lactam structure. The key intermediates were synthesized by electrophilic allylation of γ-phenylthio-functionalized γ-lactam derivatives with 2-(acetoxy)methyl acrylamides in the absence of any metal catalyst and delivered into each type of spirolactams through desulfinative hydroxylation/lactamization

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• formylbenzoate 29 has also been used in another three-component synthesis along with amines 2 and ketones 31 (Scheme 8) [82]. This Mannich/lactamization reaction achieves good yields for a broad scope of 3-substituted isoindolinones 32, in either catalyst-free conditions or using p-toluenesulfonic acid. Ortho

• procedure has been described by Singh and co-workers [85], who used formylbenzoate 29 and preformed enol ethers instead of ketones in a Mukaiyama–Mannich lactamization reaction catalysed by zinc or copper under mild conditions. A large amount of diverse isoindolinones 32 (thirty-four examples) can be built

• in this manner, although, once again, ortho-substituted anilines 2 did not render the cyclic product, as the final lactamization step is probably impeded by sterical reasons. On the other hand, silyl enol ethers of acetone, acetophenone, methyl acetate, 2-hydroxyfuran and cyclohexanone worked well

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• -methylpregabalin (1) in an analogy to literature procedures (Scheme 4) [47]. Adduct 7 was transformed to lactone 13 via nitro group reduction with NaBH4/NiCl2 followed by spontaneous lactamization. In the last step, lactam 13 was hydrolyzed and decarboxylated to give 4-methylpregabalin hydrochloride (1·HCl). We

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• prepiscibactin through five supplementary steps, including Zn(II)-induced thiazolidine formation followed by lactamization. On the basis of NOE methods, the synthetic prebiscibactin was found spectroscopically indistinguishable from the natural product. More recently, excellent results were also reported by

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• ] (Scheme 26). The formation of the products is initiated by the nucleophilic attack of either C4 or NH2 of 81 onto E-1, followed, in both cases, by elimination of HCN to give intermediates 84 and 85, respectively. The heterocyclization leading to 82 is a lactamization, whereas a ring closure via N attack

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• case the two-step protocol is followed by a lactamization and the one-pot reduction of ester and lactam groups of 18. The authors proposed a reductive anionic chain mechanism described in Scheme 10. The exposure of 14a to BH3 generates a borane–amine complex 20 whose fragmentation could be promoted by

One-pot synthesis of tetracyclic fused imidazo[1,2-a]pyridines via a three-component reaction

• Bo Yang,
• Chuanye Tao,
• Taofeng Shao,
• Jianxian Gong and
• Chao Che

Beilstein J. Org. Chem. 2016, 12, 1487–1492, doi:10.3762/bjoc.12.145

• development of new GBB-based methods for the efficient synthesis of novel polycyclic fused imidazo[1,2-a]pyridines is highly desirable. In an earlier study, we have developed a GBB/lactamization MCR strategy, which provided the rapid access to isoquinolinone-fused imidazo[1,2-a]pyridines with potent and

Study on the total synthesis of velbanamine: Chemoselective dioxygenation of alkenes with PIFA via a stop-and-flow strategy

• Huili Liu,
• Kuan Zheng,
• Xiang Lu,
• Xiaoxia Wang and
• Ran Hong

Beilstein J. Org. Chem. 2013, 9, 983–990, doi:10.3762/bjoc.9.113

• ” in a planar amide [41]. In the PIFA-promoted cyclization, lactonization was more likely to be a prominent process than lactamization. Following Tellitu’s procedure [46], we re-synthesized 13 and subjected it to the proton NMR in the presence of D2O. Three proton signals were exchanged with deuterium

Formal synthesis of (−)-agelastatin A: an iron(II)-mediated cyclization strategy

• Daisuke Shigeoka,
• Takuma Kamon and
• Takehiko Yoshimitsu

Beilstein J. Org. Chem. 2013, 9, 860–865, doi:10.3762/bjoc.9.99

• first-generation strategy employed a stereoselective thermal aziridination of azidoformate 2 and a subsequent aziridine-opening reaction to establish the vicinal trans nitrogen motif 4 [26]. The second-generation strategy involved the radical aminobromination of azidoformate 3 followed by lactamization

The diketopiperazine-fused tetrahydro-β-carboline scaffold as a model peptidomimetic with an unusual α-turn secondary structure

• Francesco Airaghi,
• Andrea Fiorati,
• Giordano Lesma,
• Manuele Musolino,
• Alessandro Sacchetti and
• Alessandra Silvani

Beilstein J. Org. Chem. 2013, 9, 147–154, doi:10.3762/bjoc.9.17

• -turn conformation. The synthesis is based on a diastereoselective Pictet–Spengler condensation to give the THBC core, followed by an intramolecular lactamization to complete the tetracyclic THBC-DKP fused ring system. The presence of conformers bearing the intramolecular thirteen-membered hydrogen bond

• in CH2Cl2 and 2,6-lutidine to give 5. The formation of the fused, tetracyclic THBC-DKP ring system was then easily achieved by removal of the N-Fmoc protecting group [49] and spontaneous lactamization to give the diketopiperazine ring of 6. The obtained compound 6 represents a valuable peptidomimetic