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Search for "tandem" in Full Text gives 382 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

  • Sayan Pramanik and
  • Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

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  • dispirocyclopentanebisoxindoles from two molecules of 3-phenacylideneoxindoles, accomplished by reduction of one molecule of 3-phenacylideneoxindole by thiol [24]. In 2017, Thennarasu et al. [25] reported the tandem oxidation/Michel-aldol reaction of 3-phenacyloxindoles for the synthesis of dispirocycliopentanebisoxindoles
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Published 27 Apr 2022

Amamistatins isolated from Nocardia altamirensis

  • Till Steinmetz,
  • Wolf Hiller and
  • Markus Nett

Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40

Graphical Abstract
  • -caprolactam moiety. Since the splitting pattern of the corresponding proton signals is consistent with 1, the lactam nitrogen must be hydroxylated in 2. Tandem MS data is consistent with this assumption (Figure 3). Compound 3 (1.8 mg) was isolated as a clear oil. Its molecular formula was established as
  • next to the ε-amino group in the lysine moiety. The assumption of a hydroxylamine function is consistent with tandem MS data, which showed mass shifts of 16 Da in the corresponding region in comparison to compound 3. Compound 5 (0.7 mg) was obtained as a clear oil. Its molecular formula of C36H53N5O10
  • conditions. The structures of these natural products were verified by high-resolution mass spectrometry, tandem mass spectrometry as well as 1D and 2D NMR analyses. Their absolute configuration is consistent with the already known amamistatin B according to a comparison of optical rotation values and NOE
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Published 30 Mar 2022

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

  • Sangram Gore,
  • Sundarababu Baskaran and
  • Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

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  • -unsaturated ketoesters, such as (E)-ethyl 4-(4-nitrophenyl)-2-oxobut-3-enoate (17), afforded the corresponding 5-unsubstituted DHPM derivative 18 in good yield (entry 6, Table 1). Similarly, heteroaromatic aldehyde derived ketoester 21, also underwent the tandem reaction to give the corresponding 5
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Published 22 Mar 2022

Regioselectivity of the SEAr-based cyclizations and SEAr-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

Graphical Abstract
  • -cd]indoles 21 from the intramolecular cyclization of Ugi adducts 20 in moderate to good yields and excellent chemo-, regio-, and diastereoselectivity (Scheme 7) [17]. Mechanistically, the reaction involves a tandem gold(I)-catalyzed dearomatization/ipso-cyclization/Michael addition sequence to
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Published 08 Mar 2022

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

  • Surendran Amrutha,
  • Sankaran Radhika and
  • Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

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  • -substituted iodobenzenes catalyzed by in situ-generated α-Fe2O3 nanoparticles. One-pot synthesis of 2-arylbenzo[b]furans via tandem Sonogashira coupling–cyclization protocol. Suggested mechanism of the Fe(III) catalyzed coupling of o-iodophenol with acetylene derivatives. Fe3O4@SiO2/Schiff base/Fe(II
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Published 03 Mar 2022

Tenacibactins K–M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum

  • Yasuhiro Igarashi,
  • Yiwei Ge,
  • Tao Zhou,
  • Amit Raj Sharma,
  • Enjuro Harunari,
  • Naoya Oku and
  • Agus Trianto

Beilstein J. Org. Chem. 2022, 18, 110–119, doi:10.3762/bjoc.18.12

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  • remaining four methylenes (H6, H7, H8, H9) were not assignable from the NMR data due to signal overlapping, but were expected to be placed between the isohexyl and the alkenyl fragments, thus establishing an isopentadecenoyl moiety. The connectivity between this aliphatic chain to the tandem
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Published 13 Jan 2022

Iron-catalyzed domino coupling reactions of π-systems

  • Austin Pounder and
  • William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

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  • reported [53]. In 2015, Kang and co-workers described a FeCl2-catalyzed tandem cyclization/cross-coupling reaction of alkyl iodides 1 with aryl Grignard reagents 2 to give arylmethyl-substituted pyrrolidines and tetrahydrofurans 3 in poor to excellent yield (Scheme 3) [54]. The concept of alkyl halide
  • tandem cross-coupling reactions was first introduced by Fürstner in 2004 who disclosed specific iodoalkanes with pendant olefins undergo cyclization prior to the anticipated cross-coupling with Grignard reagents [55]. This has since been recognized by a number of other reports, indicating a SET process
  • byproducts were detected which supports the absence of an initial oxidative addition between the alkyl iodide and the active Fe catalyst. The possibility of a radical process rather than ionic cross-coupling is supported by the tandem cyclization/cyclopropyl ring-opening reaction, similar to previous reports
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Published 07 Dec 2021

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

  • Chuanhua Qu,
  • Run Huang,
  • Yong Li,
  • Tong Liu,
  • Yuan Chen and
  • Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

Graphical Abstract
  • important C1 synthon. Its special reactivity, such as the ability to react with electrophilic, nucleophilic, and radical reagents [25][26][27][28], determines that it can participate in many types of reactions such as multicomponent reactions [29][30][31][32], tandem reactions [33][34], and insertion
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Published 02 Dec 2021

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

  • Pratibha Sharma,
  • Raakhi Gupta and
  • Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

Graphical Abstract
  • asymmetric aza-Michael reaction (aza-MR) alone or in tandem with other organic reaction(s) is an important synthetic tool to form new C–N bond(s) leading to developing new libraries of diverse types of bioactive nitrogen compounds. The synthesis and application of a variety of organocatalysts for
  • high enantioselectivities (up to 65–91%) [40]. Rajasekar et al. developed an efficient one-pot tandem rhodium(II)/chiral squaramide relay catalysis for the enantioselective construction of dihydro-β-carbolines 37 from the Michael reaction of suitably substituted indole derivatives 34 with N-sulfonyl
  • tertiary amine-thiourea catalyst (cat. 82). This cascade reaction afforded aza-Michael adducts in 77–92% yields with high ee (up to 90%) (Table 19) [55]. Du et al. developed an enantioselective catalytic tandem aminolysis/aza-Michael addition for the asymmetric total synthesis of two natural Apocynaceae
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Published 18 Oct 2021

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

  • Scott Benz and
  • Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

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  • , tandem reactions, and the total synthesis and biosynthesis of natural products. This review explores the use of α-ketol rearrangements in these contexts over the past two decades. Keywords: acyloin rearrangement; asymmetric synthesis; iminol rearrangement; ketol rearrangement; tandem reactions
  • reactions through mid-2002 have been thoroughly discussed in a past review by Paquette [1]. The current review expands on that work by providing an updated account from mid-2002 through early 2021, including the following recently developed applications: asymmetric synthesis, total synthesis, tandem
  • . Subsequent methanolysis yields α-hydroxy-β-ketoamide 23 (Figure 6). The overall reaction occurs diastereospecifically, with greater than 80% yield across each of 5 distinct amide derivatives [8]. Tandem α-ketol rearrangements Because α-ketol rearrangements can be initiated by simple reagents like a Brønsted
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Published 15 Oct 2021

Direct C(sp3)–H allylation of 2-alkylpyridines with Morita–Baylis–Hillman carbonates via a tandem nucleophilic substitution/aza-Cope rearrangement

  • Siyu Wang,
  • Lianyou Zheng,
  • Shutao Wang,
  • Shulin Ning,
  • Zhuoqi Zhang and
  • Jinbao Xiang

Beilstein J. Org. Chem. 2021, 17, 2505–2510, doi:10.3762/bjoc.17.167

Graphical Abstract
  • (sp3)–H allylic alkylation of 2-alkylpyridines with Morita–Baylis–Hillman (MBH) carbonates is described. A plausible mechanism of the reaction might involve a tandem SN2’ type nucleophilic substitution followed by an aza-Cope rearrangement. Various alkyl substituents on 2-alkylpyridines were tolerated
  • pyridylic C(sp3)–H bond (Scheme 1b). For examples, Tunge et al. developed a Pd-catalyzed intramolecular decarboxylative coupling of heterocyclic ally esters via a tandem allylation/Cope rearrangement strategy [18]; Hartwig and co-workers reported a stereo-divergent allylic substitution with azaarene
  • demonstrated a direct C(sp3)–H allylic alkylation reaction of 2-alkylpyridines with MBH carbonates with mild and simple operation. The process does not need either a base or a transition metal catalyst. The mechanism of this reaction was envisioned involving a tandem SN2’ type nucleophilic substitution
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Published 01 Oct 2021

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

  • Yi Liu,
  • Puying Luo,
  • Yang Fu,
  • Tianxin Hao,
  • Xuan Liu,
  • Qiuping Ding and
  • Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

Graphical Abstract
  • , Jiangxi Provincial People’s Hospital Affiliated to Nanchang University, 92 Aiguo Road, Nanchang, Jiangxi, 330006, China 10.3762/bjoc.17.163 Abstract Great progress has been made in the tandem annulation of enynes in the past few years. This review only presents the corresponding reactions of 1,3-enyne
  • introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles. Keywords: 1,3-enyne; functionalization; pyridine; pyrrole; tandem annulation; Introduction The pyridine moiety is an important class of six-membered N-heterocycles that is widely found
  • pyridine derivatives have been developed through the intramolecular or intermolecular tandem addition annulation/functionalization of alkynes with some N-containing compounds, such as nitriles, oximes, and imines [15][16][17][18][19]. The pyrrole structural motif is also an invaluable five-membered N
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Published 22 Sep 2021

Strategies for the synthesis of brevipolides

  • Yudhi D. Kurniawan and
  • A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

Graphical Abstract
  • 110 in 85% yield (Scheme 14). Application of a tandem 1,4/1,2-reduction to this compound under Noyori conditions gave the expected diastereomer 113 as the major product in 90% yield (dr 96:4). After protection of the resulting free secondary alcohol as the tosyl ester 114 (88%), this molecule was
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Published 14 Sep 2021

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

  • Tülay Yıldız,
  • İrem Baştaş and
  • Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

Graphical Abstract
  • intramolecular coupling of arynes by aldehydes or phenols [21][22][23][24], and Lewis acid-catalyzed cyclization of salicylaldehydes and cyclohexenones or tetralones [25]. Some other new and prominent synthesis methods of xanthenes are the tandem arylation/Friedel–Crafts reaction of o-hydroxy bisbenzylic
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Published 30 Aug 2021

Recent advances in the syntheses of anthracene derivatives

  • Giovanni S. Baviera and
  • Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

Graphical Abstract
  • sequential modifications [30], photocyclization of divinylterphenyl derivatives [31], tandem radical cyclization of (Z,Z)-1,4-bis(2-iodostyryl)benzene derivatives [32], and ring-closing olefin metathesis of tetravinylterphenyls [33] as the best-known synthetic routes. Herein, we have classified the synthetic
  • anthracene derivatives 33. The strategy involved a palladium(II)-catalyzed tandem transformation with diphenyl carboxylic acids 31 and acrylates 32 (Scheme 7) [41]. This new methodology involved a carboxyl-directed C–H alkenylation, a carboxyl-directed secondary C–H activation, an intramolecular C–C-bond
  • activation In 2009, Liang et al. reported an efficient and highly regioselective route to construct substituted tetracyclic benz[a]anthracene derivatives 115 (Scheme 26) [60]. For this purpose, the authors developed an efficient palladium-catalyzed tandem C–H activation/bis-cyclization reaction of
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Published 10 Aug 2021

Asymmetric organocatalyzed synthesis of coumarin derivatives

  • Natália M. Moreira,
  • Lorena S. R. Martelli and
  • Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

Graphical Abstract
  • dihydrocinchonine 26 in combination with trifluoracetic acid (TFA) as Brønsted acid [39]. The reaction provides pyranocoumarins 25 with three vicinal stereogenic centers in high regio-, diastereo- and enantioselectivities through a tandem allylic alkylation/intramolecular oxa-Michael addition (Scheme 7). A
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Published 03 Aug 2021

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

  • Renato L. Carvalho,
  • Amanda S. de Miranda,
  • Mateus P. Nunes,
  • Roberto S. Gomes,
  • Guilherme A. M. Jardim and
  • Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Graphical Abstract
  • amiodarone (93, antiarrhythmic activity) (Scheme 32A) [166]. The method consists of a tandem, regioselective Fe(III)-catalyzed C–H halogenation, followed by an Fe or Cu-catalyzed O-arylation to access the benzo[b]furan derivatives in high yields. Several natural products and pharmacologically active targets
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Published 30 Jul 2021

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

  • Nikita Brodyagin,
  • Martins Katkevics,
  • Venubabu Kotikam,
  • Christopher A. Ryan and
  • Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

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Published 19 Jul 2021

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

  • Pezhman Shiri,
  • Ali Mohammad Amani and
  • Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

Graphical Abstract
  • tandem reaction proceeds via formation of a Schiff-base 39 and subsequently 1,3-dipolar cycloaddition to produce the intermediate 42. Then, the intermediate 42 affords the final product 43 via an oxidative aromatization process in the presence of air or iodine (Scheme 15). To propose a precise mechanism
  • . Finally, a reductive elimination takes place to give the corresponding final product and the catalyst for the next run [51]. A tandem Click/intramolecular sulfenylation procedure for the synthesis of sulfur-cycle-fused 1,2,3-triazoles 75 and 77 was described by Xu et al. The reaction was performed through
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Published 13 Jul 2021

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

  • Feng Xiong,
  • Bo Li,
  • Chenrui Yang,
  • Liang Zou,
  • Wenbo Ma,
  • Linghui Gu,
  • Ruhuai Mei and
  • Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

Graphical Abstract
  • ] auxiliaries (Figure 1a). Besides, the cobalt(II)- [31] or nickel(II)-catalyzed [32][33], pyridine oxide (PyO)-directed tandem alkynylation/annulation was realized by Niu and Song et al., which also provided the 3-methyleneisoindolin-1-one scaffolds (Figure 1b). Notably, a sustainable cupraelectro-catalyzed
  • also proved to be a viable substrate. Thus, the corresponding isoindolone 3aa was assembled via a tandem decarboxylative C−H/C−C sequence (Scheme 3a). The practical relevance of our approach was reflected by the cleavage of the N-2-pyridylhydrazide group, yielding S-3aa (Scheme 3b). Inspired by the
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Published 08 Jul 2021

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

  • Jie Zheng,
  • Shuyu Meng and
  • Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

Graphical Abstract
  • vinyl aldehydes 13, next the cascade Prins/Friedel–Crafts reaction was examined. We started our investigations by applying aldehyde 13a as the model substrate (Scheme 5). A Lewis acid screening was carried out to identify the best catalyst for the tandem intramolecular Prins/Friedel–Crafts reaction
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Published 22 Jun 2021

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

  • Premansh Dudhe,
  • Mena Asha Krishnan,
  • Kratika Yadav,
  • Diptendu Roy,
  • Krishnan Venkatasubbaiah,
  • Biswarup Pathak and
  • Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

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  • extreme thermal conditions with the use of corrosive reagents. Much later, Larock and co-workers developed a Pd/Cu-catalyzed imino-annulation of internal alkynes [15], which paved the way for transition-metal-catalyzed cyclizations as easy access to these scaffolds. Notably, the gold-catalyzed tandem
  • cycloisomerization/Pictet–Spengler cyclization of 2-(4-aminobut-1-yn-1-yl)aniline [16], the Ru and Rh-catalyzed [2 + 2 + 2] cycloadditions of yne-ynamides [17], and the Pd-catalyzed tandem coupling-cyclization [18] are significant works in the area (Scheme 1). However, the use of toxic and expensive metal catalysts
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Published 17 Jun 2021

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

  • Joseane A. Mendes,
  • Paulo R. R. Costa,
  • Miguel Yus,
  • Francisco Foubelo and
  • Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Graphical Abstract
  • ]. Other regio- and stereoisomeric 2-pyrrolidones 80 were also prepared by a stereoselective tandem Barbier process of 79 with alkyl and aryl bromide [100]. The process was performed in this case under Barbier reaction conditions. Namely, the formation of the nucleophile (organomagnesium reagent) is
  • carried out in the presence of the electrophile (chiral imine 79). Surprisingly, both diastereomeric aldimines 79 (RS and SS) gave similar results concerning the stereochemical outcome, suggesting that the chiral sulfonamide moiety was not involved in the stereocontrol during this tandem Barbier addition
  • interest for the treatment of Alzheimer’s disease and other neurological disorders (Scheme 37). The diastereoselective synthesis of trans-5-hydroxy-6-substituted 2-piperidinones 139 was also achieved from O-benzyl protected aldimine 138 following the previously commented tandem Grignard reagent addition
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Published 12 May 2021

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

  • Jan Bartáček,
  • Jan Svoboda,
  • Martin Kocúrik,
  • Jaroslav Pochobradský,
  • Alexander Čegan,
  • Miloš Sedlák and
  • Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

Graphical Abstract
  • the addition of the boronic acid to the β-(2-hydroxyaryl)enone could be oxidized to afford optically pure 4-phenylchroman-2-one (Scheme 1). Also in 2007, Miyaura and co-workers presented the synthesis of enantioenriched 1-aryl-1H-indenes by a tandem 1,4-addition of arylboronic acids to enones and
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Published 10 May 2021

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

Graphical Abstract
  • of indium metal to produce homoallylic alcohol 156 (Scheme 37), which underwent a silyl-Prins cyclization to form polysubstituted exo-methylene THPs 157 [72]. Tandem allylation–silyl-Prins cyclization Tetrahydropyran can also be synthesized stereoselectively by sequential allylation to an aldehyde
  • strain with the existing stereogenic center (pseudoaxial group), leading to the formation of cis-tetrahydropyran 161 rather than a trans-tetrahydropyran. Floreancig and co-workers utilized a tandem allylation–silyl-Prins cyclization strategy to afford 2,6-disubstituted tetrahydropyran 167 by ionizing α,β
  • ]. Similar to Prins cyclization of allylsilanes, Dobbs and co-workers recently utilized the corresponding vinylsilane as an alternative for the synthesis of cis-2,6-dihydropyran [89][90]. The synthesis involves tandem addition of vinylsilane, followed by silyl-Prins cyclization reaction. For example, 4
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Published 29 Apr 2021
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