Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• catalyses the methylene group transfer, resulting in azonia-[3,3]-sigmatropic rearrangement, followed by regeneration of methylene imine by an elimination step [47]. The reaction proceeded in toluene at 80 °C with 20 mol % of the CPA catalyst 151 over 20 hours resulting in low to moderate

From perfluoroalkyl aryl sulfoxides to ortho thioethers

• Yang Li,
• Guillaume Dagousset,
• Emmanuel Magnier and
• Bruce Pégot

Beilstein J. Org. Chem. 2024, 20, 2108–2113, doi:10.3762/bjoc.20.181

• strategy to improve or modulate their physicochemical and biological properties [41][42][43][44][45], only few publications have reported a [3,3]-rearrangement with fluorinated molecules (Scheme 1c). In 2020, Wang and co-workers have developed a one-pot [3,3]-sigmatropic rearrangement/Haller–Bauer reaction

• chain, and the alkyl chain linking the cyano functional groups. The [3,3]-sigmatropic rearrangement of perfluoroalkyl selenoxides needs to be optimized to improve the yield and decrease the amount of reduction product. The complete evaluation of the potential of these new compounds will be provided in

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• by destabilizing the negative charge of the anion (Scheme 7c). Simply generated with Triton B (benzyltrimethylammonium hydroxide), the alcoholate of 17 smoothly (−20 °C to rt) underwent the [3,3]-sigmatropic rearrangement (75% conversion) directly affording 2,5-cyclohexadienone E-19 which was

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

• ′-binaphthalenes (BINAMs) from achiral N,N′-binaphthylhydrazines (Scheme 1). In the presence of chiral phosphoric acids (CPA 1), the reaction undergoes a simple [3,3]-sigmatropic rearrangement, giving the corresponding products 2 in good yield (up to 88%) and enantioselectivity (up to 93:7 er). The density

• functional calculations showed that the chiral phosphoric acid proton forms an H-bond with nitrogen atoms of 1 and the phosphate acts as a chiral counterion, resulting in a [3,3]-sigmatropic rearrangement with controlled stereoselectivity [14][41]. In 2017, Tan and co-workers developed an organocatalytic

• materials and supramolecules. Important chiral phosphoric acid scaffolds used in this review. Atroposelective aryl–aryl-bond formation by employing a facile [3,3]-sigmatropic rearrangement. Atroposelective synthesis of axially chiral biaryl amino alcohols 5. The enantioselective reaction of quinone and 2

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• cyclization and minimizes the competitive 2-oxonia-[3,3]-sigmatropic rearrangement pathway. The reaction was highly stereoselective and afforded the cis-2,6-dihydropyran in the presence of Lewis acid FeCl3. From DFT calculations, the authors concluded that the Prins product is formed more rapidly than the α

• formal 2-oxonia-[3,3]-sigmatropic rearrangement. Furthermore, Markó and co-workers successfully synthesized 2,6-anti-configured THP starting from allylsilane 245, following diethylaluminium chloride-promoted ene reaction and condensation with an aldehyde 246 [102]. Expected ene adduct 247 was obtained as

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

• approach consisted of a 3,3-sigmatropic rearrangement to give an all-carbon quaternary center, a ring-closing alkene metathesis to give an 8-membered ring, and the use of a single enantiomer of p-menthane-3-carboxaldehyde to make two natural alkaloids of opposite configuration. Firstly, (+)-euphococcinine

Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

• Hisham Qrareya,
• Lorenzo Meazza,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 3008–3014, doi:10.3762/bjoc.16.250

• Truce–Smiles rearrangement in aryl sulfonamides and aryl phenylsulfonates [44][45][46] or the [3,3]-sigmatropic rearrangement of sulfonium salts arising from the reaction of aryl sulfoxides and phenols [47]. To overcome this problem, the use of a metal catalyst (mainly Ni) was mandatory as reported for

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

• on a Diels–Alder cycloaddition, an intramolecular Mitsunobu reaction, a [3,3]-sigmatropic rearrangement, and a ring-closing metathesis. As an alternative to this approach, Clark et al. [86] efficiently performed a sequential Ru-catalyzed enyne metathesis in combination with a hydroboration, and an

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• intermediate. This species then undergoes [3,3]-sigmatropic rearrangement, positioning the allylic unit in a regio- and stereospecific manner, along with rearomatization to afford the products 357–360 (Scheme 57) [107]. The borylfluoromethylation of acrylamides, acrylates, and heteroaromatic-substituted alkenes

Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?

• Dominika Krištofíková,
• Juraj Filo,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2019, 15, 2948–2957, doi:10.3762/bjoc.15.290

• rearrangement; silyl ketene acetals; Introduction The Ireland–Claisen rearrangement is a reaction converting allyl esters to γ,δ-unsaturated carboxylic acids. Its key step is a [3,3]-sigmatropic rearrangement of a silyl ketene acetal, which is generated in situ by deprotonation of an allyl ester using a strong

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• ]. In this review, we shall exclusively focus on alternative strategies that rely either on a [2,3]-sigmatropic rearrangement (Scheme 1, reaction 4) or a [3,3]-sigmatropic rearrangement of cyclopropenylcarbinol derivatives (Scheme 1, reaction 5). These transformations have emerged as useful tools over

• first highlighted by Marek et al. who investigated the transposition of cyclopropenylcarbinyl esters [33][34]. The [3,3]-sigmatropic rearrangement of acetate 10a took place during filtration on silica gel and afforded alkylidene(acetoxycyclopropane) 11a in 90% yield. The ease with which the

• nature of the rearrangement (Scheme 10) [33][34]. The acidic promotor may be simply assisting the dissociation of the C4–O bond in the transition state TS3 whilst an aromatic group (R1 = Ar) would contribute to the stabilization of a developing positive charge at C4. The [3,3]-sigmatropic rearrangement

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

• 11 was converted into the trichloroimidate, and heating in xylenes permitted a [3,3]-sigmatropic rearrangement. At this stage, the trichloroimidate was transformed into an NHBoc moiety. Deprotection of the alcohol followed by Jones oxidation gave the final dipeptide isostere 13. Taguchi and co

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• the catalyst solution through a pad of Celite prior to addition of the starting material to remove AgCl. In that way we reached an 81% yield of tricycle 50. The acetoxy group again formally underwent a 1,3-shift to the benzylic position, which may also be based on a [3,3]-sigmatropic rearrangement

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

Anionic sigmatropic-electrocyclic-Chugaev cascades: accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene

• Laurence Burroughs,
• John Ritchie,
• Mkhethwa Ngwenya,
• Dilfaraz Khan,
• William Lewis and
• Simon Woodward

Beilstein J. Org. Chem. 2015, 11, 273–279, doi:10.3762/bjoc.11.31

• , substituted phenyl, 2-thienyl) to ortho-C6H4(CHO)2 undergo cascades to tetracenes on simple admixture of LiHDMS, CS2 and MeI. Acene formation proceeds by [3,3]-sigmatropic rearrangement of xanthate anions followed by 6π electrocyclisations. The reactions are terminated by E2 or anionic Chugaev-type

• reaction components maximises the yield of 7a (Table 1, runs 3–6). These results very strongly suggest unprecedented anionic [3,3]-sigmatropic rearrangement starting from 1d; another addition to the body of evidence for the importance of charge upon sigmatropic rearrangements [25][26]. In the subsequent

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• framework of B-seco limonoid natural products by means of a [3,3]-sigmatropic rearrangement are described. Detailed model studies reveal, that an Ireland–Claisen rearrangement can be employed to construct the central C9–C10 bond thereby giving access to the B-seco limonoid scaffold. However, application of

• natural product classes to inspire the synthesis of probes and reagents for chemical biology and medicinal chemistry research, we aimed at the development of a synthetic strategy to get access to the B-seco limonoid scaffold by means of a [3,3]-sigmatropic rearrangement as key step enabling the formation

• alcohol 18 and Mitsunobu reaction installed the required stereochemistry at C14. The free C14 hydroxy group was masked with protecting groups (MOM and TIPS) of different size and chemical nature to examine the face-selectivity of the [3,3]-sigmatropic rearrangement. After selective desilylation, alcohols

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• cyclohepta[cd]oxindole core 32 proved the synthetic versatility of a [3,3]-sigmatropic rearrangement for direct C–C-bond formation at the C4 position of the indole nucleus, and thus provides experimental evidence for the biosynthetic proposal. Applications to natural product synthesis Fatty acid metabolites

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• intermediate. The initially isolated nitronic ester cycloadducts underwent tin(IV)-catalyzed interconversion, presumably via zwitterion intermediates. Cycloadducts derived from the reaction at the less substituted double bond of (E)-3-methyl-1,3-pentadiene underwent a [3,3]-sigmatropic rearrangement on heating

• initial assessment of substituent effects on the rearrangement process is presented. Keywords: cycloaddition; diene; nitro; nitronate; rearrangement; Introduction We have previously reported examples of a general new [3,3]-sigmatropic rearrangement, the conversion of O-allyl nitronic esters (nitronates

• )-catalyzed [3,3]-sigmatropic rearrangement of nitronic ester 5 affords nitro compound 16 (vide infra). The rapid interconversion of nitronic esters 2 and 3 likely reflects the greater ease of rotation for the cyclo zwitterion 17. Here bond breaking and reformation is at a secondary rather than tertiary

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

• Jungho Jun,
• Hyu-Suk Yeom,
• Jun-Hyun An and
• Seunghoon Shin

Beilstein J. Org. Chem. 2013, 9, 1724–1729, doi:10.3762/bjoc.9.198

• polarization of alkynes both by a gold catalyst and a sulfonyl substituent resulted in an efficient intermolecular tandem carboalkoxylation. Reactions of linear allyl ethers are consistent with the [3,3]-sigmatropic rearrangement mechanism, while those of branched allyl ethers provided [3,3]- and [1,3

• ]-rearrangement products through the formation of a tight ion–dipole pair. Keywords: gold catalysis; intermolecular coupling; [1,3]-rearrangement; [3,3]-sigmatropic rearrangement; sulfonylacetylene; Introduction Homogeneous gold catalysis has been established during the last decade as a prominent tool in

• undergo intermolecular alkoxylation-[3,3]-sigmatropic rearrangement under Ag(I) or Au(I) catalysis [7][8], allyl ethers that are less nucleophilic due to steric reasons react more slowly and have not been known to undergo similar reactions until recently. In our previous work [9], it was shown that ester

Efficient, highly diastereoselective MS 4 Å-promoted one-pot, three-component synthesis of 2,6-disubstituted-4-tosyloxytetrahydropyrans via Prins cyclization

• Naseem Ahmed and
• Naveen Kumar Konduru

Beilstein J. Org. Chem. 2012, 8, 177–185, doi:10.3762/bjoc.8.19

• tetrahydropyrans. After 22 h stirring more side-products than the desired product were observed. This might be due to the formation of an oxo-carbenium intermediate, which further reacted in a [3,3]sigmatropic rearrangement to give another oxo-carbenium ion (Scheme 1). To optimize the reaction yield, we varied the

• conditions (Table 1, entry 9 vs entry 10). The significant improvements in product yields, reaction time and/or diastereoselectivity might be due to the prevention of the [3,3]sigmatropic rearrangement along with the dehydrating activity of MS 4 Å. In addition, we studied the stoichiometric ratio of MS 4 Å

• unsymmetrical tetrahydropyran derivatives in an economical manner. Moreover, it was observed that MS 4 Å might have a vital part in controlling the reversibility of the [3,3]sigmatropic rearrangement. Furthermore, cleavage of the 4-tosyl group under mild conditions afforded 4-hydroxytetrahydropyrans in high

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• into the angular triquinane ventricosene in six steps (Scheme 23). 6 Ring expansions involving propargyl acyloxy rearrangements Propargyl carboxylates 80 can be π-activated by gold towards 1,2-acyloxy migration and/or [3,3]-sigmatropic rearrangement. Two different, but mechanistically related

• , intermediates characterize these competitive processes, i.e., 1,2-migration via metal "carbenoid" 81 formation and [3,3]-sigmatropic rearrangement via allenyl acetate 82 as an intermediate (Scheme 24) [5][56][57]. In 2008, Toste and co-workers reported a gold(I)-catalyzed cycloisomerization of cis-pivaloyloxy

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

• Silke Dubberke,
• Muhammad Abbas and
• Bernhard Westermann

Beilstein J. Org. Chem. 2011, 7, 421–425, doi:10.3762/bjoc.7.54

• steric interference was believed to be a major obstacle of this process, this factor turned out to be unimportant. It is assumed, that the transition state during [3,3]-sigmatropic rearrangement is as shown in Scheme 3 [23][24], where the hydroxyl group is fixed in a pseudo-axial orientation, any other

Recent advances in carbocupration of α-heterosubstituted alkynes

• Ahmad Basheer and
• Ilan Marek

Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77

• undergoes a subsequent thermal [3,3]-sigmatropic rearrangement to give the corresponding nitrile 27. The presence of the organomagnesium group on 26 is essential for the rearrangement to proceed in good yield (Scheme 12). The silylcupration of N-1-alkynylsulfonylamides 28 led to the desired vinylsilane

A thermally-induced, tandem [3,3]-sigmatropic rearrangement/[2 + 2] cycloaddition approach to carbocyclic spirooxindoles

• Kay M. Brummond and
• Joshua M. Osbourn

Beilstein J. Org. Chem. 2010, 6, No. 33, doi:10.3762/bjoc.6.33

• observed, but are likely intermediates of an infrequently encountered thermal [3,3]-sigmatropic rearrangement of a propargylic acetate. Keywords: allene; propargylic acetate; spirooxindole; thermal [2 + 2] cycloaddition; thermal [3,3]-sigmatropic rearrangement; vinylidene indolin-2-one; Introduction

• 5 could be obtained by way of a thermal [3,3]-sigmatropic rearrangement of the propargylic acetate 6 to give compound 5 where R2 = OAc (Figure 2) [27]. Preparation of propargylic acetate 9a was accomplished by the addition of the lithium acetylide of 8 to N-methyl isatin (7) followed by acetylation

• allenyl acetate in intermediate 11 which in turn arises from the thermal [3,3]-sigmatropic rearrangement of 9a (Figure 3). We have briefly investigated the scope and limitations of this tandem cycloaddition reaction by varying the protecting group on the oxindole nitrogen, altering the substitution on the