Regio‐ and Stereoselective 1,3‐Oxathiolane Formation in the Reaction of Thiolactones with Optically Active Oxiranes

Fu, Changchun; Linden, Anthony; Heimgartner, Heinz

doi:10.1002/hlca.200490205

Cited by 7 publications

(2 citation statements)

References 22 publications

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“…Spirocyclic 1,3-oxathiolanes can be prepared from thionolactones and oxiranes (Scheme 21). 34 SiO 2 is used for Lewis acid activation of the oxirane reactant. The nucleophilic attack by the thiocarbonyl S-atom at the SiO 2 -activated oxirane ring proceeds with high regio-and stereoselectivity via an S N 2-type mechanism.…”

Section: 6-dioxa-4-thiaspiro[44]nonanementioning

confidence: 99%

“…The reaction of 3,4,5,6-tetrahydro-2H-pyran-2-thione with (S)-2-methyloxirane (85) (molar ratio 2:1) in anhydrous CH 2 Cl 2 at 0 °C in the presence of SiO 2 affords two spirocyclic 1,3-oxathiolane diastereomers 175 (38%) as the major products. 34 The minor spirane 175b is partially epimerized to 175a, purity 90% (Scheme 40). The analogous reaction with (R)-2-phenyloxirane (86) in anhydrous CH 2 Cl 2 at room temperature in the presence of SiO 2 affords the spirocyclic 1,3-oxathiolanes 176a,b and 177 in 54, 11, and 8% yield, respectively.…”

Section: 6-dioxa-4-thiaspiro[45]decanementioning

confidence: 99%

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Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Undheim

2016

Synthesis

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Spirocyclic scaffolds are embedded in several families of natural products. In the spirocyclic structure, the two rings constituting the spirane are linked through a common carbon atom. This review covers families of compounds that have three heteroatoms directly attached to the spirocarbon. Common heteroatoms are nitrogen, oxygen and sulfur, constituting spirocyclic orthoesters, ortholactones, orthothioesters and orthoaminals, or combinations thereof. Embedded spirocyclic scaffolds introduce steric restrictions and thereby influence bioactivity. In polymer chemistry, synthetic ortholactones may serve as monomers. Synthesis of anomeric spironucleosides will afford molecules where the basic unit is in a fixed conformation around the N-glycosidic bond. Synthesis of glycosidic and 2-deoxyglycosidic ortholactones in disaccharides and regioselective reductive cleavage of cyclic orthoesters result in stereoselective β-(1→4)-glycosidic bond formation. Pyranose and furanose free-radical chemistry via spirocyclic orthoesters can be applied in the generation of carbacyclic sugars and nucleosides. 1 Introduction 2 Heteraspiro[3.m]alkanes 3 Heteraspiro[4.m]alkanes 4 Heteraspiro[5.m]alkanes 5 Conclusion Key words tri(α-hetera)spiranes, spiroannulations, stereoselective syntheses, spirocyclic nucleosides, spirocyclic glycosides, polymer monomers 2 Heteraspiro[3.m]alkanes 2.1 Heteraspiro[3.4]octanes 2.1.1 5,8-Dioxa-1-azaspiro[3.4]octane Cyclic ketene acetals react with phenyl isocyanate to afford the corresponding spiro compounds. Scheme 1 shows a synthesis of a spirane, 6-methyl-1-phenyl-5,8-dioxa-2-oxo-1-azaspiro[3.4]octane (2). 12 In general, the β-carbon atom in the double bond of ketene acetals has an anionic character and forms an equimolar adduct with isocyanates. The adduct formation is often exothermic and may be carried out neat or in a solvent. In the preparation of 2, control of SYNTHESIS0 0

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Section: 6-dioxa-4-thiaspiro[44]nonanementioning

confidence: 99%

Section: 6-dioxa-4-thiaspiro[45]decanementioning

confidence: 99%

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Undheim

2016

Synthesis

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Reaction of Thioketones with (R)‐2‐Vinyloxirane: Regio‐ and Stereoselective Formation of (S)‐4‐Vinyl‐1,3‐oxathiolanes

Fedorov

Linden

et al. 2005

Eur J Org Chem

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The reactions of 4,4'‐dimethoxythiobenzophenone (1), 9H‐xanthene‐9‐thione (2), and adamantane‐2‐thione (3) with (R)‐2‐vinyloxirane [(R)‐6] in the presence of SiO2 in anhydrous CH2Cl2 at 0 °C or room temperature afforded the corresponding 4‐vinyl‐1,3‐oxathiolane derivatives (S)‐7, (S)‐9, and (S)‐11, respectively. The analogous BF3‐catalyzed reactions of (R)‐6 with 1,1,3,3‐tetramethylindane‐2‐thione (4) and 2,2,4,4‐tetramethyl‐3‐thioxocyclobutanone (5) in anhydrous CH2Cl2 at –65 °C or –78 °C yielded the corresponding spirocyclic 1,3‐oxathiolanes (S)‐12 and (S)‐14, respectively. The structures of (S)‐9 and (S)‐12 were established by X‐ray crystallography. In all cases, the nucleophilic thiocarbonyl S atom attacked predominantly C(2) of the Lewis acid‐activated (R)‐2‐vinyloxirane ring with inversion of the configuration through an SN2‐type mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Ring Enlargement and Sulfur‐Transfer Processes in SiO₂‐Catalyzed Reactions of Thiocarbonyl Compounds with Optically Active Oxiranes

Malaschichin

Linden

et al. 2005

Helvetica Chimica Acta

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The reactions of 1,3‐dioxolane‐2‐thione (3) with (S)‐2‐methyloxirane ((S)‐1) and with (R)‐2‐phenyloxirane ((R)‐2) in the presence of SiO2 in anhydrous dichloroalkanes led to the optically active spirocyclic 1,3‐oxathiolanes 8 with Me at C(7) and 9 with Ph at C(8), respectively (Schemes 2 and 3). The analogous reaction of 1,3‐dimethylimidazolidine‐2‐thione (4a) with (R)‐2 yielded stereoselectively (S)‐2‐phenylthiirane ((S)‐10) in 83% yield and 97% ee together with 1,3‐dimethylimidazolidin‐2‐one (11a). In the cases of 3‐phenyloxazolidine‐2‐thione (4b) and 3‐phenylthiazolidine‐2‐thione (4c), the reaction with (RS)‐2 yielded the racemic thiirane (RS)‐10, and the corresponding carbonyl compounds 11b and 11c (Scheme 4 and Table 1). The analogous reaction of 4a with 1,2‐epoxycyclohexane (= 7‐oxabicyclo[4.1.0]heptane; 7) afforded thiirane 12 and the corresponding carbonyl compound 11a (Scheme 5). On the other hand, the BF3‐catalyzed reaction of imidazolidine‐2‐thione (5) with (RS)‐2 yielded the imidazolidine‐2‐thione derivative 13 almost quantitatively (Scheme 6). In a refluxing xylene solution, 1,3‐diacetylimidazolidine‐2‐thione (6) and (RS)‐2 reacted to give two imidazolidine‐2‐thione derivatives, 13 and 14 (Scheme 7). The structures of 13 and 14 were established by X‐ray crystallography (Fig.).

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Regio‐ and Stereoselective 1,3‐Oxathiolane Formation in the Reaction of Thiolactones with Optically Active Oxiranes

Cited by 7 publications

References 22 publications

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Reaction of Thioketones with (R)‐2‐Vinyloxirane: Regio‐ and Stereoselective Formation of (S)‐4‐Vinyl‐1,3‐oxathiolanes

Ring Enlargement and Sulfur‐Transfer Processes in SiO₂‐Catalyzed Reactions of Thiocarbonyl Compounds with Optically Active Oxiranes

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Regio‐ and Stereoselective 1,3‐Oxathiolane Formation in the Reaction of Thiolactones with Optically Active Oxiranes

Cited by 7 publications

References 22 publications

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Reaction of Thioketones with (R)‐2‐Vinyloxirane: Regio‐ and Stereoselective Formation of (S)‐4‐Vinyl‐1,3‐oxathiolanes

Ring Enlargement and Sulfur‐Transfer Processes in SiO2‐Catalyzed Reactions of Thiocarbonyl Compounds with Optically Active Oxiranes

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Ring Enlargement and Sulfur‐Transfer Processes in SiO₂‐Catalyzed Reactions of Thiocarbonyl Compounds with Optically Active Oxiranes