Diastereoselective Synthesis of Substituted Tetrahydrothiophenes and -thiopyrans via Thia-Prins Cyclization Reaction

Borah, Madhurjya; Gogoi, Paramartha; Indukuri, Kiran; Saikia, Anil K.

doi:10.1021/jo502831w

Cited by 19 publications

(3 citation statements)

References 46 publications

(46 reference statements)

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“…In continuation of our interest in the synthesis of sulfur heterocyclic compounds, [23,24] we envisioned that β,γ-unsaturated ketone, 1-(4-chlorophenyl)but-3-en-1-one (1 b) under Lewis acidic conditions would generate enolate which will react with 1,4-dithiane-2,5-diol (2) in an aldol type fashion to give intermediate hydroxy ketone 3 which after Michael reaction will give tetrahydrothiophene 4 b (Scheme 1). However, in contrast, when the reaction was performed with 10 mol% of Bi (OTf) 3 in dichloromethane (DCM), compound 5 b was obtained as a single diastereomer in 25% yield after 60 h. Increasing the amount of Bi(OTf) 3 to 30 mol% gave 60% yield (entry 2, Table 1), and further increase of Bi(OTf) 3 to one equivalent could not enhance the yield even after 60 h, (entry 4, Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…The sulfur analogs of oligosaccharides are known to be potential enzyme inhibitors . There are numerous methods for the synthesis of tertrahydrothiophenes, namely, intramolecular ring‐opening of epoxides by thiolates, hydrothiolation of nonactivated olefins, photolysis of diazo compounds, and thia‐Prins cyclization reactions . Tetrahydrothiophenes are also synthesized using domino Michael‐aldol and double Michael reactions.…”

Section: Introductionmentioning

confidence: 99%

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Bismuth(III)‐Triflate‐Catalyzed Highly Diastereoselective Synthesis of Substituted Tetrahydrothiophene via Tandem Isomerization, Michael and Aldol Reactions

Borthakur

Saikia

2019

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bismuth(III)‐Triflate‐Catalyzed Highly Diastereoselective Synthesis of Substituted Tetrahydrothiophene via Tandem Isomerization, Michael and Aldol Reactions

Borthakur

Saikia

2019

ChemistrySelect

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“…We also studied the reaction of thioacrylates 74 (similar to acrylyl enol ethers) under the same reaction conditions and observed the formation of tetrahydrothiophenes 75 and tetrahydrothiopyrans 76 in moderate to good yields and high diastereoselectivities (Scheme 42 ). 54 Both aromatic and aliphatic substituents on the alkyne side chain and branched chain gave good yields. Electron-withdrawing groups on the aromatic ring gave better yields compared to electron-donating groups.…”

Section: Prins Cyclization Reactionsmentioning

confidence: 98%

Synthesis of Heterocyclic Scaffolds via Prins, Oxonium-Ene and Related Cyclization Reactions

Saikia¹

2022

Synlett

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A variety of oxygen, nitrogen and sulfur heterocyclic compounds are synthesized via one-pot multicomponent, Prins–, aza–Prins–, thia–Prins–, oxonium–ene–, iminium–ene–, and thionium–ene–cyclization reactions. The reactions proceeds with high diastereo– and region–selectivity. Importantly, C–C, C–N, C–O and C–S bonds are formed in a single step. These procedures are extended for the synthesis of biologically active molecules and natural products.

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A Radical Reaction for the Synthesis of 3‐Substituted Dihydrothiopyrans under Photosensitized Conditions

et al. 2018

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We report the synthesis of thiopyran derivatives under photosensitized conditions. This method is of interest for its reactionm echanism andi sanovel synthetic route to heterocycles.Cyclic ether moietiesa re often found not only in sugars but also in av ariety of bioactive compounds. [1] Studies on compoundsw ith tetrahydrofuran or tetrahydropyran scaffolds are generallyd eemed valuable. [2] In contrast, S-containing heterocycles are not well understood compared to O-heterocycles because cyclic sulfides are encountered much lessf requently than cyclic ethers. [3] However,r ecent reports revealed that some thiopyrans-the sulfur analogues of pyrans-exhibit unique biological activities, attracting increasing interest from researchers in the pharmaceutical industry. [4] Someu seful pharmaceutical agents possessing thiopyran scaffolds have been reported, including cephalosporins [4a] and dithiathromboxane A 2 . [4c] Furthermore,t he chemical behavior of S-containing heterocycles often differs greatlyf rom that of O-analogues. For example, in the Diels-Alder reaction, furan can be involved as a diene substrate under mild conditions; [5] harsh conditions of high temperature and high pressure are required for thiophene because of its aromaticity. [6] These results show that Sanalogues of useful cyclic ethers can presentu nexpected and interesting properties.Severala pproaches can be used for the synthesis of S-containing heterocycles, including thia-Prins cyclization, [7] Michael/ aldol reaction, [8] thionium-ene cyclization reaction, [9] oxidative CÀHb ond functionalization, [10] and so forth. [11] In this context, an ovel approach was proposed using radical reactions because it is well known that radicalr eactions show different reactivity and selectivity compared with ordinary ionic reactions. [12] Accordingly,wef ocused on the radical reaction to synthesize dihydrothiophenes or dihydrothiopyrans reported by Journet'sg roup around 20 years ago (Scheme 1). [13] Their Scheme1.Synthesis of S-containing heterocycles using the double radical addition-b-cleavage process.EWG = electron-withdrawing group; AIBN = 2,2'-azobis(2-methylpropionitrile).

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Diastereoselective Synthesis of Substituted Tetrahydrothiophenes and -thiopyrans via Thia-Prins Cyclization Reaction

Abstract: Tetrahydrothiophenes and -thiopyrans have been efficiently synthesized from thioacrylates via thia-Prins cyclization reaction mediated by trimethylsilyltrifluoromethanesulfonate with good diastereoselectivity and in good to high yields.

Cited by 19 publications

References 46 publications

Bismuth(III)‐Triflate‐Catalyzed Highly Diastereoselective Synthesis of Substituted Tetrahydrothiophene via Tandem Isomerization, Michael and Aldol Reactions

Bismuth(III)‐Triflate‐Catalyzed Highly Diastereoselective Synthesis of Substituted Tetrahydrothiophene via Tandem Isomerization, Michael and Aldol Reactions

Synthesis of Heterocyclic Scaffolds via Prins, Oxonium-Ene and Related Cyclization Reactions

A Radical Reaction for the Synthesis of 3‐Substituted Dihydrothiopyrans under Photosensitized Conditions

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