Darunee Soorukram

Regioselective C2 Sulfonylation of Indoles Mediated by Molecular Iodine

A facile and general method for regioselective C2 sulfonylation reaction of indoles mediated by iodine is described. The 2-sulfonylated products were obtained up to 96% yield under mild reaction conditions (room temperature, 2 h).

Iodine–PPh3-mediated C3-sulfenylation of indoles with sodium sulfinates

3-(Alkylsulfanyl)- and 3-(arylsulfanyl)indoles were efficiently prepared by the reaction of indoles with sodium sulfinates mediated by iodine–PPh3 in ethanol. The salient features of the present protocol are simplicity, high efficiency, non-anhydrous conditions, environmentally friendly reagents and solvent, and short reaction time.

Four-Component Benzyne Coupling Reactions: A Concise Total Synthesis of Dehydroaltenuene B

A four-component coupling reaction of 3,5-dimethoxybenzyne with 2-methyl-2-cyclohexenylmagnesium chloride, carbon dioxide, and iodine was utilized as a key step in the first total synthesis of dehydroaltenuene B.

Radical cyclization/ipso-1,4-aryl migration cascade: asymmetric synthesis of 3,3-difluoro-2-propanoylbicyclo[3.3.0]octanes.

A novel method for the asymmetric synthesis of 3,3-difluoro-2-propanoylbicyclo-[3.3.0]octanes involves an unprecedented intramolecular radical cyclization/ipso-1,4-aryl migration cascade.

Iodine-catalyzed Sulfonylation of Arylacetylenic Acids and Arylacetylenes with Sodium Sulfinates: Synthesis of Arylacetylenic Sulfones

A highly efficient and generally applicable iodine-catalyzed reaction of arylacetylenic acids and arylacetylenes with sodium sulfinates for the synthesis of arylacetylenic sulfones was developed. The methodology has the advantages of a metal-free strategy, easy to handle reagents, functional group tolerance, a wide range of arylacetylenic acids and arylacetylenes, and easy access to arylacetylenic sulfones.

An Improved Synthesis of Vinyl- and β-Iodovinyl Sulfones by a Molecular Iodine-Mediated One-Pot Iodosulfonation-Dehydroiodination Reaction

Abstract An improved one-pot method to synthesize vinyl sulfones from unsaturated systems by using molecular iodine/sodium arenesulfinate/sodium acetate as reagents was described. Vinyl sulfones derived from styrene derivatives were generally obtained in good to excellent yields except for those bearing strong electron releasing substituent. Aliphatic alkenes and activated alkenes gave the corresponding vinyl sulfone products in moderate to good yields. Arylacetylenes yielded the respective β-iodovinyl sulfones in good yields while low yield was observed with aliphatic terminal alkyne. The potentials of the method entail simplicity, short reaction time, non-anhydrous reaction conditions, employing inexpensive, non-metallic reagent and integrating two reactions that are commonly accomplished separately into a single operation. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

Synthesis of gem-Difluoromethylenated Bicyclo[m.n.0]alkan-1-ols and Their Ring-Expansion to gem-Difluoromethylenated Macrocyclic Lactones

Fluoride-catalyzed stereoselective nucleophilic addition of PhSCF(2)SiMe(3) (1) to α-carboethoxycycloalkanones 2 followed by intramolecular radical cyclization of the resulting cis-3 adduct afforded the corresponding gem-difluoromethylenated bicyclic compounds 4, which underwent ring-expansion followed by the Baeyer-Villiger-type oxidation of the resulting macrocyclic ketone intermediates to give gem-difluoromethylenated macrocyclic lactones 5.

Asymmetric Synthesis of gem-Difluoromethylenated Dihydroxypyrrolizidines and Indolizidines

An asymmetric synthesis of gem-difluoromethylenated dihydroxypyrrolizidines and indolizidines is described. The fluoride-catalyzed nucleophilic addition of PhSCF(2)SiMe(3) (1) to chiral imides was achieved in satisfactory yields to provide mixtures of syn- and anti-isomers 6-9 with moderate to good diastereoselectivities. Reductive cleavage of the phenylsulfanyl group followed by intramolecular radical cyclization of the syn-isomers 6-9 occurred under refluxing conditions to afford the corresponding gem-difluoromethylenated 1-azabicyclic compounds 10-13 in moderate yields as a separable mixture of cis- and trans-isomers. The cis-isomers of compounds 10 and 12 and trans-13 were readily transformed to gem-difluoromethylenated dihydroxypyrrolizidines 20 and 27 and indolizidine 28, respectively, by reductive cleavage of the hydroxyl group and organometallic addition followed by hydrogenolysis.

Synthesis of gem-difluoromethylenated polycyclic cage compounds.

The synthesis of gem-difluoromethylenated polycyclic cage compounds, utilizing PhSCF2SiMe3 as a gem-difluoromethylene building block, is described. The fluoride-catalyzed nucleophilic addition of PhSCF2SiMe3 to both maleic anhydride-cyclopentadiene and maleic anhydride-cyclohexadiene adducts was accomplished with high stereoselectivity to provide the corresponding adducts that were treated with Grignard reagents, followed by acid-catalyzed lactonization to afford the corresponding γ-butyrolactones, each as a single isomer. These γ-butyrolactones underwent intramolecular radical cyclization to give the corresponding tetracyclic cage γ-butyrolactones, which were employed as precursors for the synthesis of gem-difluoromethylenated tetracyclic cage lactols or tetracyclic cage furans, upon treatment with Grignard reagents.

Asymmetric Synthesis of gem-Difluoromethylenated Linear Triquinanes via Cascade gem-Difluoroalkyl Radical Cyclization

An asymmetric synthesis of gem-difluoromethylenated linear triquinanes is described exploiting the synthetic utilities of PhSCF2TMS (5) as a (•)CF2(-) building block. The strategy involves fluoride-catalyzed nucleophilic addition of PhSCF2TMS (5) to chiral ketocyclopentenes 6 to provide silylated adducts 9 or alcohol derivatives 10 and 11. Subsequent cascade radical cyclization of the gem-difluoroalkyl radical generated from silylated adducts 9 or alcohols 10 and 11 afforded gem-difluoromethylenated linear triquinanes 16 as an approximate 1:1 mixture of two diastereomers (16A and 16B). Alternatively, a convenient asymmetric synthesis of gem-difluoromethylenated linear triquinanes 16A can be accomplished by oxidation of 16a (R = H) to provide ketotriquinane 17 followed by a highly stereoselective nucleophilic addition to 17 employing DIBAL, NaBH4, and various Grignard reagents.